wifi: rtw89: mac: add to get DLE reserved quota

The reserved quota of DLE (data link engine) is used for processing next
packet. Add this to get quota number, and then WiFi 7 chips can use them.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20231124071703.132549-3-pkshih@realtek.com