mvebu: switch to kernel 5.4

Last reports with kernel 5.4 have all been positive [1], so let's open
this to a wider range of testers.

[1] https://github.com/openwrt/openwrt/pull/2804

Signed-off-by: Adrian Schmutzler <[email protected]>

target/linux/mvebu/Makefile

@@ -11,7 +11,7 @@ BOARDNAME:=Marvell EBU Armada
 FEATURES:=fpu usb pci pcie gpio nand squashfs ramdisk boot-part rootfs-part
 SUBTARGETS:=cortexa9 cortexa53 cortexa72
 
-KERNEL_PATCHVER:=4.19
+KERNEL_PATCHVER:=5.4
 KERNEL_TESTING_PATCHVER:=5.4
 
 include $(INCLUDE_DIR)/target.mk