mtd: Replace kcalloc() with devm_kcalloc()

Replace kcalloc() with devm_kcalloc() to prevent memory leaks in case of
errors.

Fixes: 78c0824 ("mtd: Support kmsg dumper based on pstore/blk")
Cc: stable@vger.kernel.org # v5.10+
Signed-off-by: Jiasheng Jiang <jiashengjiangcool@gmail.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

Author: Jiasheng Jiang

drivers/mtd/mtdpstore.c

@@ -417,11 +417,11 @@ static void mtdpstore_notify_add(struct mtd_info *mtd)
 	}
 
 	longcnt = BITS_TO_LONGS(div_u64(mtd->size, info->kmsg_size));
-	cxt->rmmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL);
-	cxt->usedmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL);
+	cxt->rmmap = devm_kcalloc(&mtd->dev, longcnt, sizeof(long), GFP_KERNEL);
+	cxt->usedmap = devm_kcalloc(&mtd->dev, longcnt, sizeof(long), GFP_KERNEL);
 
 	longcnt = BITS_TO_LONGS(div_u64(mtd->size, mtd->erasesize));
-	cxt->badmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL);
+	cxt->badmap = devm_kcalloc(&mtd->dev, longcnt, sizeof(long), GFP_KERNEL);
 
 	/* just support dmesg right now */
 	cxt->dev.flags = PSTORE_FLAGS_DMESG;
@@ -527,9 +527,6 @@ static void mtdpstore_notify_remove(struct mtd_info *mtd)
 	mtdpstore_flush_removed(cxt);
 
 	unregister_pstore_device(&cxt->dev);
-	kfree(cxt->badmap);
-	kfree(cxt->usedmap);
-	kfree(cxt->rmmap);
 	cxt->mtd = NULL;
 	cxt->index = -1;
 }