rtw88: update tx descriptor of mgmt and reserved page packets

Previous settings for TX descriptors of and reserved page packets
are insufficient.

For the sequence number of packets downloaded to reserved page, it
should be filled by hardware.
And for ps-poll packets in reserved page, to prevent AID being
changed by hardware, NAVUSEHDR should be set.
Additionally, the rate should be adjusted based on the current band
for mgmt and reserved page packets.

Signed-off-by: Tzu-En Huang <tehuang@realtek.com>
Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200717064937.27966-4-yhchuang@realtek.com