rtw88: store firmware feature in firmware header

Some functions need the support of firmware with special version.
In order to get the feature of current firmware, we store the information
in firmware header and parse after firmware is loaded. The current feature
list in firmware header includes checking leave lps via C2H and
supported lps deep mode.

Signed-off-by: Chin-Yen Lee <timlee@realtek.com>
Signed-off-by: Tzu-En Huang <tehuang@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201030084826.9034-3-tehuang@realtek.com