mtd: spi-nor: drop unused <linux/of_platform.h>

There's nothing used in the SPI NOR core from <linux/of_platform.h>,
drop the header inclusion.

Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20250307-spi-nor-headers-cleanup-v1-3-c186a9511c1e@linaro.org
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>

Author: ambarus

drivers/mtd/spi-nor/core.c

@@ -18,7 +18,6 @@
 #include <linux/mtd/spi-nor.h>
 #include <linux/mutex.h>
 #include <linux/of.h>
-#include <linux/of_platform.h>
 #include <linux/regulator/consumer.h>
 #include <linux/sched/task_stack.h>
 #include <linux/sizes.h>