rtw88: add phy_info debugfs to show Tx/Rx physical status

This commit adds several Tx/Rx physical information to phy_info
debugfs for 8822B/8822C. By this debugfs, we can know physical
information, such as Tx/Rx rate, RSSI, EVM,SNR, etc. The
information is gotten from the packets of Tx/Rx path. It has
no impact for the performance of 8822B/8822C.

In the fields, we may meet different kinds of problems, but
we may have no professional instrument to check them. At
this moment, this debugfs is a good tool, and it may provide
useful information for debug.

Signed-off-by: Tsang-Shian Lin <thlin@realtek.com>
Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
Reviewed-by: Chris Chiu <chiu@endlessm.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>