generic: fitblk: close block device if mapping image failed

In case a broken fit image is present on flash the fitblk driver would
not map any /dev/fit* devices, but also not always close the block device
the image resides on. In case of ubiblock devices this is fatal as one
then cannot remove the ubiblock device (-EBUSY), and hence cannot replace
the broken image.
Always close the block device in case no sub-image was mapped.

Signed-off-by: Daniel Golle <[email protected]>
(cherry picked from commit 2b9c81d1cbc65eeb9304b7274058418efa8a9c78)

target/linux/generic/pending-6.6/510-block-add-uImage.FIT-subimage-block-driver.patch

@@ -656,7 +656,7 @@ Signed-off-by: Daniel Golle <[email protected]>
 +		add_fit_subimage_device(bdev, slot++, start_sect, nr_sects, true);
 +	}
 +
-+	if (!found || !slot)
++	if (!slot)
 +		goto out_bootconf;
 +
 +	dev_info(dev, "mapped %u uImage.FIT filesystem sub-image%s as /dev/fit%s%u%s\n",
@@ -675,7 +675,7 @@ Signed-off-by: Daniel Golle <[email protected]>
 +	kfree(bootconf);
 +	kfree(fit);
 +out_blkdev:
-+	if (!found || ret)
++	if (!slot)
 +		blkdev_put(bdev, &_fitblk_claim_ptr);
 +
 +	return ret;