Revert "mac80211 adjust QCA9561 PA bias"

This reverts commit f9ff282 as during
upstream patch review process nbd pointed out, that this patch needs
more work:

 "The patch looks wrong to me. I'm pretty sure that AR_CH0_TOP2 is the
  correct register, the definition has an explicit check for 9561 as well.
  I believe this patch works by accident because it avoids writing a wrong
  value to that register."

1. https://lore.kernel.org/all/91c58969-c60e-2f41-00ac-737786d435ae@nbd.name

Signed-off-by: Petr Štetiar <ynezz@true.cz>