bcm53xx: drop DTS based workaround for serial support in procd

Specifying serial in bootargs is not needed since the commit
ffeb3704 ("procd: update to git HEAD"). It's thanks to the procd
commit 2cfc26f8456a ("inittab: detect active console from kernel if no
console= specified").

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>

target/linux/bcm53xx/patches-5.10/320-ARM-dts-BCM5301X-Add-serial-to-the-bootargs.patch

-From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
-Subject: [PATCH] ARM: dts: BCM5301X: Add serial= to the bootargs
-MIME-Version: 1.0
-Content-Type: text/plain; charset=UTF-8
-Content-Transfer-Encoding: 8bit
-
-It's enough to have proper stdout-path for getting serial working but
-for some reason LEDE doesn't offer "Please press Enter to activate this
-console." unless ttyS0 is specified.
-
-This is a workaround to get serial working in LEDE.
-
-Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
----
-
---- a/arch/arm/boot/dts/bcm47081-tplink-archer-c5-v2.dts
-+++ b/arch/arm/boot/dts/bcm47081-tplink-archer-c5-v2.dts
-@@ -12,7 +12,7 @@
- 	model = "TP-LINK Archer C5 V2";
- 
- 	chosen {
--		bootargs = "earlycon";
-+		bootargs = "console=ttyS0,115200 earlycon";
- 	};
- 
- 	memory@0 {
---- a/arch/arm/boot/dts/bcm47094-luxul-abr-4500.dts
-+++ b/arch/arm/boot/dts/bcm47094-luxul-abr-4500.dts
-@@ -13,7 +13,7 @@
- 	model = "Luxul ABR-4500 V1";
- 
- 	chosen {
--		bootargs = "earlycon";
-+		bootargs = "console=ttyS0,115200 earlycon";
- 	};
- 
- 	memory@0 {
---- a/arch/arm/boot/dts/bcm47094-luxul-xbr-4500.dts
-+++ b/arch/arm/boot/dts/bcm47094-luxul-xbr-4500.dts
-@@ -13,7 +13,7 @@
- 	model = "Luxul XBR-4500 V1";
- 
- 	chosen {
--		bootargs = "earlycon";
-+		bootargs = "console=ttyS0,115200 earlycon";
- 	};
- 
- 	memory@0 {
---- a/arch/arm/boot/dts/bcm47189-luxul-xap-1440.dts
-+++ b/arch/arm/boot/dts/bcm47189-luxul-xap-1440.dts
-@@ -12,7 +12,7 @@
- 	model = "Luxul XAP-1440 V1";
- 
- 	chosen {
--		bootargs = "earlycon";
-+		bootargs = "console=ttyS0,115200 earlycon";
- 	};
- 
- 	memory@0 {
---- a/arch/arm/boot/dts/bcm47189-luxul-xap-810.dts
-+++ b/arch/arm/boot/dts/bcm47189-luxul-xap-810.dts
-@@ -12,7 +12,7 @@
- 	model = "Luxul XAP-810 V1";
- 
- 	chosen {
--		bootargs = "earlycon";
-+		bootargs = "console=ttyS0,115200 earlycon";
- 	};
- 
- 	memory@0 {
---- a/arch/arm/boot/dts/bcm47094-luxul-xap-1610.dts
-+++ b/arch/arm/boot/dts/bcm47094-luxul-xap-1610.dts
-@@ -12,7 +12,7 @@
- 	model = "Luxul XAP-1610 V1";
- 
- 	chosen {
--		bootargs = "earlycon";
-+		bootargs = "console=ttyS0,115200 earlycon";
- 	};
- 
- 	memory@0 {
---- a/arch/arm/boot/dts/bcm47094-luxul-xwr-3150-v1.dts
-+++ b/arch/arm/boot/dts/bcm47094-luxul-xwr-3150-v1.dts
-@@ -13,7 +13,7 @@
- 	model = "Luxul XWR-3150 V1";
- 
- 	chosen {
--		bootargs = "earlycon";
-+		bootargs = "console=ttyS0,115200 earlycon";
- 	};
- 
- 	memory@0 {
---- a/arch/arm/boot/dts/bcm47094-phicomm-k3.dts
-+++ b/arch/arm/boot/dts/bcm47094-phicomm-k3.dts
-@@ -13,6 +13,10 @@
- 	compatible = "phicomm,k3", "brcm,bcm47094", "brcm,bcm4708";
- 	model = "Phicomm K3";
- 
-+	chosen {
-+		bootargs = "console=ttyS0,115200";
-+	};
-+
- 	memory@0 {
- 		device_type = "memory";
- 		reg = <0x00000000 0x08000000>,
---- a/arch/arm/boot/dts/bcm47094-luxul-xwc-2000.dts
-+++ b/arch/arm/boot/dts/bcm47094-luxul-xwc-2000.dts
-@@ -13,7 +13,7 @@
- 	model = "Luxul XWC-2000 V1";
- 
- 	chosen {
--		bootargs = "earlycon";
-+		bootargs = "console=ttyS0,115200 earlycon";
- 	};
- 
- 	memory@0 {