mtd: spi-nor: add SPI_NOR_HAS_LOCK flag

We can't determine this purely by manufacturer type (see commit
67b9bcd36906 ("mtd: spi-nor: fix Spansion regressions (aliased with
Winbond)")), and it's not autodetectable by anything like SFDP. So make
a new flag for it.

Signed-off-by: Brian Norris <[e-mail]>
Reviewed-by: Ezequiel Garcia <[e-mail]>
Tested-by: Ezequiel Garcia <[e-mail]>

drivers/mtd/spi-nor/spi-nor.c

···
 #define SPI_NOR_DUAL_READ	BIT(5)	/* Flash supports Dual Read */
 #define SPI_NOR_QUAD_READ	BIT(6)	/* Flash supports Quad Read */
 #define USE_FSR			BIT(7)	/* use flag status register */
+#define SPI_NOR_HAS_LOCK	BIT(8)	/* Flash supports lock/unlock via SR */
 };
 
 #define JEDEC_MFR(info)	((info)->id[0])
···
 
 	if (JEDEC_MFR(info) == SNOR_MFR_ATMEL ||
 	    JEDEC_MFR(info) == SNOR_MFR_INTEL ||
-	    JEDEC_MFR(info) == SNOR_MFR_SST) {
+	    JEDEC_MFR(info) == SNOR_MFR_SST ||
+	    info->flags & SPI_NOR_HAS_LOCK) {
 		write_enable(nor);
 		write_sr(nor, 0);
 		spi_nor_wait_till_ready(nor);
···
 	mtd->_read = spi_nor_read;
 
 	/* NOR protection support for STmicro/Micron chips and similar */
-	if (JEDEC_MFR(info) == SNOR_MFR_MICRON) {
+	if (JEDEC_MFR(info) == SNOR_MFR_MICRON ||
+			info->flags & SPI_NOR_HAS_LOCK) {
 		nor->flash_lock = stm_lock;
 		nor->flash_unlock = stm_unlock;
 		nor->flash_is_locked = stm_is_locked;