rockchip: switch to kernel 5.10

This target has testing support for more than half a year now.
Time to switch.

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

target/linux/rockchip/Makefile

@@ -7,8 +7,7 @@ BOARDNAME:=Rockchip
 FEATURES:=ext4 audio usb usbgadget display gpio fpu pci pcie rootfs-part boot-part squashfs
 SUBTARGETS:=armv8
 
-KERNEL_PATCHVER=5.4
-KERNEL_TESTING_PATCHVER=5.10
+KERNEL_PATCHVER=5.10
 
 define Target/Description
 	Build firmware image for Rockchip SoC devices.