mtd: autcpu12-nvram: Convert driver to platform_device

Because we can have a single kernel to support multiple machines, we
need to make loading specific drivers for the target platform only.
For this, driver is converted to the platform driver.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/maps/Kconfig b/drivers/mtd/maps/Kconfig
index 53850f1..dbe7df1 100644
--- a/drivers/mtd/maps/Kconfig
+++ b/drivers/mtd/maps/Kconfig
@@ -373,7 +373,7 @@
 	  have such a board, say 'Y'.
 
 config MTD_AUTCPU12
-	tristate "NV-RAM mapping AUTCPU12 board"
+	bool "NV-RAM mapping AUTCPU12 board"
 	depends on ARCH_AUTCPU12
 	help
 	  This enables access to the NV-RAM on autronix autcpu12 board.