mtd: nand: mxs_nand: use self init

Instead of completing initialization via scan_bbt callback use
NAND self init to initialize the GPMI (MXS) NAND controller.

Suggested-by: Scott Wood <oss@buserror.net>
Signed-off-by: Stefan Agner <stefan.agner@toradex.com>
diff --git a/drivers/mtd/nand/Kconfig b/drivers/mtd/nand/Kconfig
index 94fbf89..4db259f 100644
--- a/drivers/mtd/nand/Kconfig
+++ b/drivers/mtd/nand/Kconfig
@@ -143,6 +143,7 @@
 config NAND_MXS
 	bool "MXS NAND support"
 	depends on MX23 || MX28 || MX6 || MX7
+	select SYS_NAND_SELF_INIT
 	imply CMD_NAND
 	select APBH_DMA
 	select APBH_DMA_BURST if ARCH_MX6 || ARCH_MX7