mtd: nand: rename NAND_USE_FLASH_BBT

Recall the recently added prefix requirements:
 * "NAND_" for flags in nand.h, used in nand_chip.options
 * "NAND_BBT_" for flags in bbm.h, used in nand_chip.bbt_options
        or in nand_bbt_descr.options

Thus, I am changing NAND_USE_FLASH_BBT to NAND_BBT_USE_FLASH.

Again, this flag is found in bbm.h and so should NOT be used in the
"nand_chip.options" field.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/drivers/mtd/nand/mxc_nand.c b/drivers/mtd/nand/mxc_nand.c
index ed68fde3..ca42c8f 100644
--- a/drivers/mtd/nand/mxc_nand.c
+++ b/drivers/mtd/nand/mxc_nand.c
@@ -1179,7 +1179,7 @@
 		this->bbt_td = &bbt_main_descr;
 		this->bbt_md = &bbt_mirror_descr;
 		/* update flash based bbt */
-		this->bbt_options |= NAND_USE_FLASH_BBT;
+		this->bbt_options |= NAND_BBT_USE_FLASH;
 	}
 
 	init_completion(&host->op_completion);