mtd: virt-concat: free duplicate generated name

mtd: virt-concat: free duplicate generated name

Every MTD registration runs mtd_virt_concat_create_join().  Once a
virtual concat has already been registered, the function builds the same
name again and takes the equal-name branch.  That branch skips to the
next item without freeing the newly allocated string.

Free the temporary name before continuing.

Fixes: 43db6366fc2d ("mtd: Add driver for concatenating devices")
Cc: stable@vger.kernel.org
Signed-off-by: Xu Rao <raoxu@uniontech.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>