mtd: spi-nor: fix silent truncation in spi_nor_read()

spi_nor_read() assigns the result of 'ssize_t spi_nor_read_data()'
to the 'int ret' variable, while 'ssize_t' is a 64-bit type and *int*
is a 32-bit type on the 64-bit machines. This silent truncation isn't
really valid, so fix up the variable's type.

Fixes: 59451e12 ("mtd: spi-nor: change return value of read/write")
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>

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

@@ -2545,7 +2545,7 @@ static int spi_nor_read(struct mtd_info *mtd, loff_t from, size_t len,
 			size_t *retlen, u_char *buf)
 {
 	struct spi_nor *nor = mtd_to_spi_nor(mtd);
-	int ret;
+	ssize_t ret;
 
 	dev_dbg(nor->dev, "from 0x%08x, len %zd\n", (u32)from, len);