layerscape: switch to kernel 5.4

Switch to kernel 5.4 in Makefile.

Signed-off-by: Yangbo Lu <[email protected]>

target/linux/layerscape/Makefile

@@ -8,7 +8,7 @@ include $(TOPDIR)/rules.mk
 
 BOARD:=layerscape
 BOARDNAME:=NXP Layerscape
-KERNEL_PATCHVER:=4.14
+KERNEL_PATCHVER:=5.4
 FEATURES:=squashfs nand usb pcie gpio fpu ubifs ext4
 SUBTARGETS:=armv8_64b armv7