zynq: 6.1: set testing kernel

Allow selecting 6.1 as testing kernel on zynq.

Tested-by: Luis Araneda <[email protected]> # Zybo Z7-20
Signed-off-by: Nick Hainke <[email protected]>

target/linux/zynq/Makefile

@@ -19,6 +19,7 @@ define Target/Description
 endef
 
 KERNEL_PATCHVER:=5.15
+KERNEL_TESTING_PATCHVER:=6.1
 
 include $(INCLUDE_DIR)/target.mk