ath9k: remove ->config_pci_powersave() redundant argument

We always call ->config_pci_powersave() with both restore and power_off
arguments equal to 0 or both equal to 1, so merge them into one
argument.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>