Include ieee802_11_common.c in wpa_supplicant build unconditionally

Include ieee802_11_common.c in wpa_supplicant build unconditionally

This is needed for number of items and it was possible to make a build
configuration that did not include ieee802_11_common.c while still
trying to use functions from there. While it would be possible to add
NEED_80211_COMMON=y to all the cases where this file is needed, the
extra complexity from this is not really justifiable anymore, so include
the file unconditionally.

Signed-off-by: Jouni Malinen <j@w1.fi>