Add a new vendor sub-command to implement Spatial Reuse feature.
Userspace enables SR feature with specific configuration parameters. The
driver/firmware upon receiving the command, enables the SR feature if it
is supported by the currently connected AP. The driver may reject the
command if it cannot enable the SR with the configured parameters. The
driver sends events to userspace to indicate when SR feature is enabled
or disabled internally. Userspace can also query SR feature related
parameters and statistics from the driver/firmware as needed.
Change-Id: Ie203576d4ace691e37a1c5eea379f562bf416835
CRs-Fixed: 3298975
6e707dac35