qla2xxx: Fix scsi_host leak on qlt_lport_register callback failure

This patch fixes a possible scsi_host reference leak in qlt_lport_register(),
when a non zero return from the passed (*callback) does not call drop the
local reference via scsi_host_put() before returning.

This currently does not effect existing tcm_qla2xxx code as the passed callback
will never fail, but fix this up regardless for future code.

Cc: Chad Dupuis <chad.dupuis@qlogic.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>