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>
diff --git a/arch/xtensa/Kconfig.debug b/arch/xtensa/Kconfig.debug
index af7da74..53ae08e 100644
--- a/arch/xtensa/Kconfig.debug
+++ b/arch/xtensa/Kconfig.debug
@@ -4,7 +4,7 @@
 
 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/