imx6: add 5.10 as testing kernel

So anyone interested can help with testing.

Signed-off-by: Petr Štetiar <[email protected]>

target/linux/imx6/Makefile

@@ -12,7 +12,7 @@ CPU_TYPE:=cortex-a9
 CPU_SUBTYPE:=neon
 
 KERNEL_PATCHVER:=5.4
-KERNEL_TESTING_PATCHVER:=5.4
+KERNEL_TESTING_PATCHVER:=5.10
 
 include $(INCLUDE_DIR)/target.mk