[SCSI] bfa: fix missing unlock on error in bfad_iocmd_cfg_trunk()

Add the missing unlock before return from function bfad_iocmd_cfg_trunk()
in the error handling case.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: Vijaya Mohan Guvva <vmohan@brocade.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>