mtd: spi-nor: core: correct type of i

The i should be signed to find out the end of the loop. Otherwise,
i >= 0 is always true and loop becomes infinite. Make its type to be
int.

Fixes: 6a9eda34 ("mtd: spi-nor: core: set mtd->eraseregions for non-uniform erase map")
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Reviewed-by: Michael Walle <mwalle@kernel.org>
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20240304090103.818092-1-usama.anjum@collabora.com

drivers/mtd/spi-nor/core.c

@@ -3373,7 +3373,7 @@ static u32
 spi_nor_get_region_erasesize(const struct spi_nor_erase_region *region,
 			     const struct spi_nor_erase_type *erase_type)
 {
-	u8 i;
+	int i;
 
 	if (region->overlaid)
 		return region->size;