Software antenna tuning is broken because of an function
ordering problem during rt2x00link_tuner().

rt2x00link_precalculate_signal()
rt2x00leds_led_quality()
rt2x00lib_antenna_diversity()

rt2x00link_precalculate_signal() will reset the quality TX/RX counters,
however rt2x00lib_antenna_diversity() requires the RX counter to
see what RSSI value must be used for a particular antenna.
We can't change the ordering since rt2x00lib_antenna_diversity() might
reset other statistics which are needed by the function called earlier.

Move the reset of the quality TX/RX counters into a seperate function
and move the call to after rt2x00lib_antenna_diversity().
Signed-off-by: NIvo van Doorn <IvDoorn@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

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

Restrict drivers to only access link_qual structure during
link tuning. The contents of these fields are for the drivers
and all fields are allowed to be changed to values the driver
considers correct.

This means that some fields need to be moved outside of this
structure to restrict access only to rt2x00link itself.
This allows some code to be moved outside of the rt2x00.h header
and into rt2x00link.c.
Signed-off-by: NIvo van Doorn <IvDoorn@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Move link and antenna tuning into a seperate file named rt2x00link.c,
this makes the interface to the link tuner a lot cleaner.
Signed-off-by: NIvo van Doorn <IvDoorn@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>