xtensa: nommu: add MMU dependency to DEBUG_TLB_SANITY

TLB sanity checking code depends on full MMU presence and may not be
built in noMMU confgiuration.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/Kconfig.debug

@@ -4,7 +4,7 @@ source "lib/Kconfig.debug"
 
 config DEBUG_TLB_SANITY
 	bool "Debug TLB sanity"
-	depends on DEBUG_KERNEL
+	depends on DEBUG_KERNEL && MMU
 	help
 	  Enable this to turn on TLB sanity check on each entry to userspace.
 	  This check can spot missing TLB invalidation/wrong PTE permissions/