mtd: spi-nor: include mtd.h header for struct mtd_info definition

So far struct spi_nor was using just a pointer to struct mtd_info so it
wasn't needed to have it fully defined there. After recent change we
embed whole struct so we need to include a proper header.

Fixes: 1976367173 ("mtd: spi-nor: embed struct mtd_info within struct spi_nor")
Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

include/linux/mtd/spi-nor.h

@@ -12,6 +12,7 @@
 
 #include <linux/bitops.h>
 #include <linux/mtd/cfi.h>
+#include <linux/mtd/mtd.h>
 
 /*
  * Manufacturer IDs
@@ -117,8 +118,6 @@ enum spi_nor_option_flags {
 	SNOR_F_USE_FSR		= BIT(0),
 };
 
-struct mtd_info;
-
 /**
  * struct spi_nor - Structure for defining a the SPI NOR layer
  * @mtd:		point to a mtd_info structure