FT: Differentiate between FT for station and for AP in build

FT: Differentiate between FT for station and for AP in build

Previously, CONFIG_IEEE80211R enabled build that supports FT for both
station mode and AP mode. However, in most wpa_supplicant cases only
station mode FT is required and there is no need for AP mode FT.

Add support to differentiate between station mode FT and AP mode FT in
wpa_supplicant builds by adding CONFIG_IEEE80211R_AP that should be used
when AP mode FT support is required in addition to station mode FT. This
allows binary size to be reduced for builds that require only the
station side FT functionality.

Signed-off-by: Ilan Peer <ilan.peer@intel.com>