staging: rtl8712: Change _LED_STATE enum in rtl871x driver to avoid conflicts with LED namespace

Adding led support for phy causes namespace conflicts for some
phy drivers.

The rtl871 driver declared an enum for representing LED states. The enum
contains constant LED_OFF which conflicted with declaration found in
linux/leds.h. LED_OFF changed to LED_STATE_OFF
In order to avoid a possible future collision LED_ON was changed to
LED_STATE_ON as well.
Signed-off-by: NZach Brown <zach.brown@ni.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>