mtd: nand: gpmi: use correct member for checking NAND_BBT_USE_FLASH

This has been moved from .options to .bbt_options meanwhile. So, it
currently checks for something totally different (NAND_OWN_BUFFERS) and
decides according to that.

Artem Bityutskiy: the options were moved in
a40f7341 mtd: nand: consolidate redundant flash-based BBT flags

Artem Bityutskiy: CCing -stable

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Acked-by: Huang Shijie <b32955@freescale.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Cc: stable@kernel.org [3.2+]
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>