wifi: rtw89: add DIG register struct to share common algorithm

Since control register address for DIG are different per IC, add a new
struct rtw89_dig_regs in chip info for each IC to define their own address.

Signed-off-by: Eric Huang <echuang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220908051257.25353-2-pkshih@realtek.com