Fixes gcc '-Wunused-but-set-variable' warning:

drivers/scsi/lpfc/lpfc_nvme.c: In function 'lpfc_new_nvme_buf':
drivers/scsi/lpfc/lpfc_nvme.c:2238:24: warning:
 variable 'sgl_size' set but not used [-Wunused-but-set-variable]
  int bcnt, num_posted, sgl_size;
                        ^
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>