[SCSI] qla4xxx: Correct early completion of pending mbox.

Check for Firmware Hang (AF_FW_RECOVERY) after mailbox command
has gained access to ensure that the mailbox command does not
wait un-necessarily during a firmware recovery and prevent
premature mailbox timeout which will lead to back to back reset's.

Signed-off-by: Lalit Chandivade <lalit.chandivade@qlogic.com>
Signed-off-by: Vikas Chaudhary <vikas.chaudhary@qlogic.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>