imx6: switch to Linux 4.14

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Tested-by: Koen Vandeputte <koen.vandeputte@ncentric.com>

target/linux/imx6/Makefile

@@ -14,7 +14,7 @@ CPU_TYPE:=cortex-a9
 CPU_SUBTYPE:=neon
 MAINTAINER:=Luka Perkov <luka@openwrt.org>
 
-KERNEL_PATCHVER:=4.9
+KERNEL_PATCHVER:=4.14
 
 include $(INCLUDE_DIR)/target.mk