ARM: 8298/1: ARM_KERNMEM_PERMS only works with MMU enabled

The recently added ARM_KERNMEM_PERMS feature works by manipulating
the kernel page tables, which obviously requires an MMU. Trying
to enable this feature when the MMU is disabled results in a lot
of compile errors in mm/init.c, so let's add a Kconfig dependency
to avoid that case.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mm/Kconfig

@@ -1012,6 +1012,7 @@ config ARCH_SUPPORTS_BIG_ENDIAN
 
 config ARM_KERNMEM_PERMS
 	bool "Restrict kernel memory permissions"
+	depends on MMU
 	help
 	  If this is set, kernel memory other than kernel text (and rodata)
 	  will be made non-executable. The tradeoff is that each region is