mtd: SC520CDP should depend on MTD_CONCAT

Toralf Förster found a compile error when CONFIG_MTD_SC520CDP=y and
CONFIG_MTD_CONCAT=n:

drivers/built-in.o: In function `init_sc520cdp':
sc520cdp.c:(.init.text+0xb4de): undefined reference to `mtd_concat_create'
drivers/built-in.o: In function `cleanup_sc520cdp':
sc520cdp.c:(.exit.text+0x14bc): undefined reference to `mtd_concat_destroy'

This patch fixes it.
Signed-off-by: Daniel Drake <dsd@gentoo.org>
Signed-off-by: Josh Boyer <jwboyer@gmail.com>

drivers/mtd/maps/Kconfig

@@ -78,7 +78,7 @@ config MTD_PNC2000
 
 config MTD_SC520CDP
 	tristate "CFI Flash device mapped on AMD SC520 CDP"
-	depends on X86 && MTD_CFI
+	depends on X86 && MTD_CFI && MTD_CONCAT
 	help
 	  The SC520 CDP board has two banks of CFI-compliant chips and one
 	  Dual-in-line JEDEC chip. This 'mapping' driver supports that