mtd: sharpslpart: Fix unsigned comparison to zero

The unsigned variable log_num is being assigned a return value
from the call to sharpsl_nand_get_logical_num that can return
-EINVAL.

Detected using Coccinelle:
./drivers/mtd/parsers/sharpslpart.c:207:6-13: WARNING: Unsigned expression compared with zero: log_num > 0

Fixes: 8a4580e4 ("mtd: sharpslpart: Add sharpslpart partition parser")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

drivers/mtd/parsers/sharpslpart.c

@@ -165,10 +165,10 @@ static int sharpsl_nand_get_logical_num(u8 *oob)
 
 static int sharpsl_nand_init_ftl(struct mtd_info *mtd, struct sharpsl_ftl *ftl)
 {
-	unsigned int block_num, log_num, phymax;
+	unsigned int block_num, phymax;
+	int i, ret, log_num;
 	loff_t block_adr;
 	u8 *oob;
-	int i, ret;
 
 	oob = kzalloc(mtd->oobsize, GFP_KERNEL);
 	if (!oob)