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

spi_nor_read_raw() 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: f384b352cb ("mtd: spi-nor: parse Serial Flash Discoverable Parameters (SFDP) tables")
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

@@ -2866,7 +2866,7 @@ static int spi_nor_hwcaps_pp2cmd(u32 hwcaps)
  */
 static int spi_nor_read_raw(struct spi_nor *nor, u32 addr, size_t len, u8 *buf)
 {
-	int ret;
+	ssize_t ret;
 
 	while (len) {
 		ret = spi_nor_read_data(nor, addr, len, buf);