mtd: nand: mxs_nand_spl: Fix to remove twise 'NAND' print

SPL from nand will print 'NAND' in boot_from_devices based on the image_loader name, remove the extra 'NAND ' in mxs_nand_spl driver.

After the fix:
-------------
U-Boot SPL 2017.01-rc2-gf84dd8b (Jan 02 2017 - 22:24:19) Trying to boot from NANDNAND : 512 MiB

Original behaviour:
-------------------
U-Boot SPL 2017.01-rc2-gf84dd8b-dirty (Jan 02 2017 - 23:17:00) Trying to boot from NAND: 512 MiB

---
 drivers/mtd/nand/mxs_nand_spl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index ff28df4..b6c9208 100644
@@ -153,7 +153,7 @@ static int mxs_nand_init(void)
 	nand_chip.numchips = 1;
 
 	/* identify flash device */
-	puts("NAND : ");
+	puts(": ");
 	if (mxs_flash_ident(mtd)) {
 		printf("Failed to identify\n");
 		return -1;

1.9.1