MTD: nand: mxs_nand_spl: Fix empty function pointer for BBT

The initialization function calls a nand_chip.scan_bbt(mtd) but
scan_bbt is never initialized resulting in an undefined function
pointer.  This will direct the function pointer to nand_default_bbt
defined in the same file.

Signed-off-by: Adam Ford <aford173@gmail.com>
Acked-by: Stefan Agner <stefan.agner@toradex.com>
diff --git a/drivers/mtd/nand/raw/mxs_nand_spl.c b/drivers/mtd/nand/raw/mxs_nand_spl.c
index 2d7bbe8..c628f3a 100644
--- a/drivers/mtd/nand/raw/mxs_nand_spl.c
+++ b/drivers/mtd/nand/raw/mxs_nand_spl.c
@@ -185,6 +185,7 @@
 	mtd = nand_to_mtd(&nand_chip);
 	/* set mtd functions */
 	nand_chip.cmdfunc = mxs_nand_command;
+	nand_chip.scan_bbt = nand_default_bbt;
 	nand_chip.numchips = 1;
 
 	/* identify flash device */