[MTD] [NAND] atmel_nand can be modular

There's no reason to prevent the Atmel NAND driver from
building as a module.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Håvard Skinnemoen <haavard.skinnemoen@atmel.com>
Acked-by: Andrew Victor <linux@maxim.org.za>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/nand/Kconfig

@@ -272,7 +272,7 @@ config MTD_NAND_CS553X
 	  If you say "m", the module will be called "cs553x_nand.ko".
 
 config MTD_NAND_ATMEL
-	bool "Support for NAND Flash / SmartMedia on AT91 and AVR32"
+	tristate "Support for NAND Flash / SmartMedia on AT91 and AVR32"
 	depends on ARCH_AT91 || AVR32
 	help
 	  Enables support for NAND Flash / Smart Media Card interface