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>

common/splash_source.c

@@ -162,7 +162,7 @@ static inline int splash_init_usb(void)
 }
 #endif
 
-#ifdef CONFIG_CMD_SATA
+#ifdef CONFIG_SATA
 static int splash_init_sata(void)
 {
 	return sata_initialize();