pxa: move mmc drivers to drivers/mmc

introduce new macro CONFIG_PXA_MMC to activate it

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
diff --git a/include/configs/pxa255_idp.h b/include/configs/pxa255_idp.h
index fa53cf4..d1c2c65 100644
--- a/include/configs/pxa255_idp.h
+++ b/include/configs/pxa255_idp.h
@@ -119,7 +119,6 @@
  */
 #include <config_cmd_default.h>
 
-#define CONFIG_CMD_MMC
 #define CONFIG_CMD_FAT
 #define CONFIG_CMD_DHCP
 
@@ -249,7 +248,11 @@
 						/* valid baudrates */
 #define CONFIG_SYS_BAUDRATE_TABLE	{ 9600, 19200, 38400, 57600, 115200 }
 
+#ifdef CONFIG_MMC
+#define CONFIG_PXA_MMC
+#define CONFIG_CMD_MMC
 #define CONFIG_SYS_MMC_BASE		0xF0000000
+#endif
 
 /*
  * Stack sizes