net: atlantic: Define aq_pm_ops conditionally on CONFIG_PM

For s390, gcc with W=1 reports
drivers/net/ethernet/aquantia/atlantic/aq_pci_func.c:458:32: error:
  'aq_pm_ops' defined but not used [-Werror=unused-const-variable=]
  458 | static const struct dev_pm_ops aq_pm_ops = {
      |                                ^~~~~~~~~

The only use of aq_pm_ops is conditional on CONFIG_PM.
The definition of aq_pm_ops and its functions should also
be conditional on CONFIG_PM.

Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>