This commit merges the driver_ops structures and implementations from
hostapd/driver*.[ch] into src/drivers. This is only an initial step and
there is room for number of cleanups to share code between the hostapd
and wpa_supplicant parts of the wrappers to avoid unnecessary source
code duplication.
No need for a separate driver_ops handler for setting DTIM period since
this is always set at the same time with the Beacon data. Beacon
interval is still set separately since it is consider per-radio
parameter (Beacon data and DTIM period are per-BSS parameters).
Try to match PRI/SEC channel with neighboring 20/40 MHz BSSes per
IEEE 802.11n/D7.0 11.14.3.2. This is not yet complete implementation,
but at least some parts of the 40 MHz coex are improved.
40 MHz operation maybe rejected (i.e., fall back to using 20 MHz) or
pri/sec channels may be switched if needed.
driver.h contains the definitions needed in driver wrapper
implementations (driver_*.c) and driver_i.h contains the definitions
that are used in core hostapd code to interact with the driver wrappers.
