Kconfig: Add CONFIG_SATA to enable SATA

At present CONFIG_CMD_SATA enables the 'sata' command which also brings
in SATA support. Some boards may wish to enable SATA without the command.
Add a separate CONFIG to permit this.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/fs/fat/fat.c b/fs/fat/fat.c
index a71bad1..9ad18f9 100644
--- a/fs/fat/fat.c
+++ b/fs/fat/fat.c
@@ -1251,7 +1251,7 @@
 	}
 
 #if defined(CONFIG_IDE) || \
-    defined(CONFIG_CMD_SATA) || \
+    defined(CONFIG_SATA) || \
     defined(CONFIG_SCSI) || \
     defined(CONFIG_CMD_USB) || \
     defined(CONFIG_MMC)