[SCSI] libfc: Handle discovery failure during ctlr link down

While we wait for GPN_FT response, if the ctlr link goes down, the stack
generates a completion for GPN_FT with error FC_EXCH_CLOSED, and reports a
discovery error. Discovery is not retried in this case, and rightly so.
However, the 'pending' flag stays set, which does not allow subsequent
discovery to succeed as GPN_FT will never be issued. Fix it by clearing the
pending flag when the discovery fails due to GPN_FT failure.

Signed-off-by: Bhanu Prakash Gollapudi <bprakash@broadcom.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>