[PATCH] rt2x00: Fix rfkill handling

As reported by Modestas Vainius, enabling rkfill in 1 driver and
disabling it in a second could cause a NULL pointer exception when
the rfkill-disabled driver still sets the CONFIG_SUPPORT_HW_BUTTON flag.

Furthermore, rfkill expects the timeout as a value in milliseconds
instead of jiffies. Also increase the timeout to a second,
since this 250ms would be overkill.

Also the flag DEVICE_ENABLED_RADIO_HW is causing problems
for devices which do not support the hardware button
while rfkill is enabled in the driver.

To remidy this we should inverse the flag and its meaning,
rename the flag to DEVICE_DISABLED_RADIO_HW this means that
by default the radio is enabled by the hardware button (if present)
and can only be disabled explicitely.

Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>