rt2500: disable PS by default

It is know that PS cause issues on that old devices, disable it by
default.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Gertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --cc drivers/net/wireless/rt2x00/rt2500pci.c
Simple merge

diff --cc drivers/net/wireless/rt2x00/rt2500usb.c
Simple merge