api: Define a default mmc max device

Define a default number of 1 for mmc max device if board config didn't
specify one.

Signed-off-by: Emmanuel Vadot <manu@bidouilliste.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

api/api_storage.c

@@ -43,6 +43,9 @@ struct stor_spec {
 
 static struct stor_spec specs[ENUM_MAX] = { { 0, 0, 0, 0, NULL }, };
 
+#ifndef CONFIG_SYS_MMC_MAX_DEVICE
+#define CONFIG_SYS_MMC_MAX_DEVICE	1
+#endif
 
 void dev_stor_init(void)
 {