Add a structure for power parameters including base,
offset, limit and a function to get tx power parameters.
Then, refine flow to get tx power index through the
function.
Signed-off-by: NZong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: NYan-Hsuan Chuang <yhchuang@realtek.com>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>