mtd: atmel_nand: check NFC busy flag by HSMC_SR instead of NFC cmd regs

Currently the driver read NFC command registers to get NFC busy flag.
Actually this flag also can be get by reading HSMC_SR register.

Use the read NFC command registers need mapping a huge memory region.
To save the mapped memory region, we change to check NFC busy flag by
reading HSMC_SR register.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Josh Wu <josh.wu@atmel.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
diff --git a/drivers/mtd/nand/atmel_nand_nfc.h b/drivers/mtd/nand/atmel_nand_nfc.h
index 85b8ca6..4d5d262 100644
--- a/drivers/mtd/nand/atmel_nand_nfc.h
+++ b/drivers/mtd/nand/atmel_nand_nfc.h
@@ -35,6 +35,7 @@
 #define		NFC_CTRL_DISABLE	(1 << 1)
 
 #define ATMEL_HSMC_NFC_SR	0x08		/* NFC Status Register */
+#define		NFC_SR_BUSY		(1 << 8)
 #define		NFC_SR_XFR_DONE		(1 << 16)
 #define		NFC_SR_CMD_DONE		(1 << 17)
 #define		NFC_SR_DTOE		(1 << 20)