qla4xxx: Fix smatch warning in func qla4xxx_get_ep_param

Fix following smatch warning:-
 drivers/scsi/qla4xxx/ql4_os.c:1752 qla4xxx_get_ep_param() warn: variable dereferenced before check 'qla_ep' (see line 1745)

Signed-off-by: Vikas Chaudhary <vikas.chaudhary@qlogic.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: Christoph Hellwig <hch@lst.de>