wcn36xx: set self STA default HT parameters

These default HT parameters are required for self STA entry.
In example, set the HT capable of self STA entry for bss
configuration in mesh allows the MCS rate to be used. Otherwise,
only legacy rate will be used.

Signed-off-by: Chun-Yeow Yeoh <yeohchunyeow@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>