scsi: libfc: Free skb in fc_disc_gpn_id_resp() for valid cases

In fc_disc_gpn_id_resp(), skb is supposed to get freed in all cases except
for PTR_ERR. However, in some cases it didn't.

This fix is to call fc_frame_free(fp) before function returns.

Link: https://lore.kernel.org/r/20200729081824.30996-2-jhasan@marvell.com
Reviewed-by: Girish Basrur <gbasrur@marvell.com>
Reviewed-by: Santosh Vernekar <svernekar@marvell.com>
Reviewed-by: Saurav Kashyap <skashyap@marvell.com>
Reviewed-by: Shyam Sundar <ssundar@marvell.com>
Signed-off-by: Javed Hasan <jhasan@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>