sf: Flash power up read-only based on idcode0

Using macro's for flash power up read-only access code
leads wrong behaviour hence use idcode0 for runtime
detection, hence the flash which require this functionality
gets detected at runtime.

Tested-by: Jagan Teki <jteki@openedev.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Jagan Teki <jteki@openedev.com>
diff --git a/drivers/mtd/spi/sf_internal.h b/drivers/mtd/spi/sf_internal.h
index 8f586ee..b8692c6 100644
--- a/drivers/mtd/spi/sf_internal.h
+++ b/drivers/mtd/spi/sf_internal.h
@@ -66,6 +66,7 @@
 #define SPI_FLASH_CFI_MFR_MACRONIX	0xc2
 #define SPI_FLASH_CFI_MFR_SST		0xbf
 #define SPI_FLASH_CFI_MFR_WINBOND	0xef
+#define SPI_FLASH_CFI_MFR_ATMEL		0x1f
 
 /* Erase commands */
 #define CMD_ERASE_4K			0x20