wifi: rtw89: phy: add parser to support RX gain dynamic setting flow

Add RX gain offset dynamic setting flow according to different bands
and bandwidths. RX gain offset values will be different according to
different channel bands, therefore, this dynamic mechanism is needed
while channel is changed. Add this to parse data from the element of
firmware file, and then we can use them easier at runtime.

Signed-off-by: Chung-Hsuan Hung <hsuan8331@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20240105064228.36580-3-pkshih@realtek.com