spl: nand: remove code duplication

spl: nand: remove code duplication

Remove code duplication in spl_nand_load_image().

No functional changes.

Signed-off-by: Nikita Kiryanov <nikita@compulab.co.il>
Cc: Scott Wood <scottwood@freescale.com>
Cc: Igor Grinberg <grinberg@compulab.co.il>
Acked-by: Scott Wood <scottwood@freescale.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heiko Schocher <hs@denx.de>
[trini: Add back cast to unsigned long of spl_image.load_addr]
Signed-off-by: Tom Rini <trini@konsulko.com>