splash_source: add support for ubifs formatted nand

Add support for loading splash image from NAND Flash formatted with a (UBI) filesystem.

Signed-off-by: Eran Matityahu <eran.m@variscite.com>
Cc: Heiko Schocher <hs@denx.de>
Cc: Igor Grinberg <grinberg@compulab.co.il>
Cc: Tom Rini <trini@konsulko.com>
Cc: Nikita Kiryanov <nikita@compulab.co.il>
Cc: Stefano Babic <sbabic@denx.de>
Acked-by: Nikita Kiryanov <nikita@compulab.co.il>

include/splash.h

@@ -43,6 +43,8 @@ struct splash_location {
 	enum splash_flags flags;
 	u32 offset;	/* offset from start of storage */
 	char *devpart;  /* Use the load command dev:part conventions */
+	char *mtdpart;	/* MTD partition for ubi part */
+	char *ubivol;	/* UBI volume-name for ubifsmount */
 };
 
 int splash_source_load(struct splash_location *locations, uint size);