realtek: switch to kernel 5.10

The usual testers did their tests. Now we need testers who use the
master builds.

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

target/linux/realtek/Makefile

@@ -10,8 +10,7 @@ DEVICE_TYPE:=basic
 FEATURES:=ramdisk squashfs
 SUBTARGETS:=generic
 
-KERNEL_PATCHVER:=5.4
-KERNEL_TESTING_PATCHVER:=5.10
+KERNEL_PATCHVER:=5.10
 
 define Target/Description
 	Build firmware images for Realtek RTL83xx based boards.