ramips: improve support for Xiaomi Miwifi Nano

This patch does the following things:
1. mark u-boot-env writable
2. add bootcount support
   Currently, u-boot has a flag_boot_success env variable to reset.
   Also reset it in our firmware to follow the behavior in vendor's
   firmware.
3. disable usb support
   This router doesn't have usb port at all.
4. increase spi clock to 40MHz
5. fix pinmux groups

Signed-off-by: Chuanhong Guo <gch981213@gmail.com>

target/linux/ramips/base-files/etc/init.d/bootcount

@@ -7,5 +7,8 @@ boot() {
 	samknows,whitebox-v8)
 		fw_setenv bootcount 0
 		;;
+	xiaomi,miwifi-nano)
+		fw_setenv flag_boot_success 1
+		;;
 	esac
 }

target/linux/ramips/dts/mt7628an_xiaomi_miwifi-nano.dts

@@ -52,12 +52,20 @@
 &pinctrl {
 	state_default: pinctrl0 {
 		gpio {
-			ralink,group = "refclk", "wled_an", "gpio";
+			ralink,group = "gpio", "refclk", "wdt", "wled_an";
 			ralink,function = "gpio";
 		};
 	};
 };
 
+&ehci {
+	status = "disabled";
+};
+
+&ohci {
+	status = "disabled";
+};
+
 &wmac {
 	status = "okay";
 	ralink,mtd-eeprom = <&factory 0x4>;
@@ -73,7 +81,7 @@
 	m25p80@0 {
 		compatible = "jedec,spi-nor";
 		reg = <0>;
-		spi-max-frequency = <10000000>;
+		spi-max-frequency = <40000000>;
 
 		partitions {
 			compatible = "fixed-partitions";
@@ -89,7 +97,6 @@
 			partition@30000 {
 				label = "u-boot-env";
 				reg = <0x30000 0x10000>;
-				read-only;
 			};
 
 			factory: partition@40000 {

target/linux/ramips/image/mt76x8.mk

@@ -560,7 +560,7 @@ define Device/xiaomi_miwifi-nano
   IMAGE_SIZE := 16064k
   DEVICE_VENDOR := Xiaomi
   DEVICE_MODEL := MiWiFi Nano
-  DEVICE_PACKAGES := kmod-usb2 kmod-usb-ohci kmod-usb-ledtrig-usbport
+  DEVICE_PACKAGES := uboot-envtools
   SUPPORTED_DEVICES += miwifi-nano
 endef
 TARGET_DEVICES += xiaomi_miwifi-nano