rtw88: fix DIG min setting

DIG min is expected to be set according to chip. And actually we assigned
it under each chip information. However, we didn't use the setting when we
did DIG process. It is unexpected, so we fix it.

Signed-off-by: Zong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210319054218.3319-4-pkshih@realtek.com