wifi: rt2x00: correct wrong BBP register in RxDCOC calibration

Refer to Mediatek vendor driver RxDCOC_Calibration() function, when
performing gainfreeze calibration, we should write register 140
instead of 141. This fix can reduce the total calibration time from
6 seconds to 1 second.

Signed-off-by: Shiji Yang <yangshiji66@outlook.com>
Acked-by: Stanislaw Gruszka <stf_xl@wp.pl>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/TYAP286MB0315B13B89DF57B6B27BB854BCAFA@TYAP286MB0315.JPNP286.PROD.OUTLOOK.COM