mtd: spi-nor: support vcc-supply regulator

SPI NOR flashes needs power supply to work properly. The power supply
maybe software controllable per board design. So add the support
for an vcc-supply regulator.

Signed-off-by: Peng Fan <[email protected]>
Reviewed-by: Marco Felsch <[email protected]>
[ta: move devm_regulator_get_enable() to spi_nor_probe().]
Signed-off-by: Tudor Ambarus <[email protected]>
Reviewed-by: Pratyush Yadav <[email protected]>
Signed-off-by: Pratyush Yadav <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: MrVan

drivers/mtd/spi-nor/core.c

@@ -17,6 +17,7 @@
 #include <linux/mtd/spi-nor.h>
 #include <linux/mutex.h>
 #include <linux/of_platform.h>
+#include <linux/regulator/consumer.h>
 #include <linux/sched/task_stack.h>
 #include <linux/sizes.h>
 #include <linux/slab.h>
@@ -3587,6 +3588,10 @@ static int spi_nor_probe(struct spi_mem *spimem)
 	char *flash_name;
 	int ret;
 
+	ret = devm_regulator_get_enable(dev, "vcc");
+	if (ret)
+		return ret;
+
 	nor = devm_kzalloc(dev, sizeof(*nor), GFP_KERNEL);
 	if (!nor)
 		return -ENOMEM;