scsi: qla2xxx: Unregister chrdev if module initialization fails

commit c794d24e upstream.

If module initialization fails after the character device has been
registered, unregister the character device. Additionally, avoid
duplicating error path code.

Cc: Himanshu Madhani <hmadhani@marvell.com>
Cc: Giridhar Malavali <giridhar.malavali@qlogic.com>
Fixes: 6a03b4cd ("[SCSI] qla2xxx: Add char device to increase driver use count") # v2.6.35.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>