xtensa: make MMU-related configuration options depend on MMU

MMUv3 and HIGHMEM support are available only on configurations with MMU,
don't show them otherwise.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index 7feca8d..480a7d5 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -197,6 +197,7 @@
 
 config INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
 	bool "Initialize Xtensa MMU inside the Linux kernel code"
+	depends on MMU
 	default y
 	help
 	  Earlier version initialized the MMU in the exception vector
@@ -226,6 +227,7 @@
 
 config HIGHMEM
 	bool "High Memory Support"
+	depends on MMU
 	help
 	  Linux can use the full amount of RAM in the system by
 	  default. However, the default MMUv2 setup only maps the