wifi: rtw89: add BW info for both TX and RX in phy_info

In order to debug performance issue intuitively, add bandwidth information
into debugfs entry phy_info. After applying this patch, it looks like:

 TX rate [0]: HE 2SS MCS-11 GI:0.8 BW:80 (hw_rate=0x19b) ==> agg_wait=1 (3500)
 RX rate [0]: HE 2SS MCS-9 GI:0.8 BW:80  (hw_rate=0x199)

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/20221021091601.39884-1-pkshih@realtek.com