scsi: qla2xxx: avoid unused-function warning

When NVMe support is disabled, we get a couple of harmless warnings:

drivers/scsi/qla2xxx/qla_nvme.c:667:13: error: 'qla_nvme_unregister_remote_port' defined but not used [-Werror=unused-function]
drivers/scsi/qla2xxx/qla_nvme.c:634:13: error: 'qla_nvme_abort_all' defined but not used [-Werror=unused-function]
drivers/scsi/qla2xxx/qla_nvme.c:604:12: error: 'qla_nvme_wait_on_rport_del' defined but not used [-Werror=unused-function]

This replaces the preprocessor checks in the code with equivalent
compiler conditionals, which lets gcc drop the unused functions without
warning, and is nicer to read.

Fixes: e84067d7 ("scsi: qla2xxx: Add FC-NVMe F/W initialization and transport registration")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>