[rdk-b][mt7986][wifi-hal][Add get and set guard interval functions]

[Description]
Add get and set guard interval functions. And record GI value in the file.
The function getRadioGuardInterval and setRadioGuardInterval is deprecated, So I implement them just call the corresponding new functions.
Use iw instead of hostapd beacause hostapd can not set GI in he mode.

[Release-log]
N/A

1 file changed