bcm63xx: switch to Kernel 5.10

Bump the last missing target to Kernel 5.10. While this requires a work
around to boot it will allow more people to test the new Kernel before
the upcomming release.

Signed-off-by: Paul Spooren <[email protected]>

target/linux/bcm63xx/Makefile

@@ -10,8 +10,8 @@ BOARD:=bcm63xx
 BOARDNAME:=Broadcom BCM63xx
 SUBTARGETS:=generic smp
 FEATURES:=squashfs usb atm pci pcmcia usbgadget
-KERNEL_PATCHVER:=5.4
-KERNEL_TESTING_PATCHVER:=5.10
+
+KERNEL_PATCHVER:=5.10
 
 define Target/Description
 	Build firmware images for Broadcom based xDSL/routers