Convert CONFIG_ARCH_MAP_SYSMEM to Kconfig

This converts the following to Kconfig:
   CONFIG_ARCH_MAP_SYSMEM

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/Kconfig b/arch/Kconfig
index ba2c57d..ee32e83 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -1,3 +1,7 @@
+config ARCH_MAP_SYSMEM
+	depends on SANDBOX || NDS32
+	def_bool y
+
 config CREATE_ARCH_SYMLINK
 	bool