These are not allowed in ISO C++ (and well, not really in ISO C either,
but that does not result in compiler warning without pedantic
compilation).
Since ieee802_11_common.h may end up getting pulled into C++ code for
some external interfaces, it is more convenient to keep it free of these
cases. Pull in ieee802_11_defs.h to get enum phy_type defined and move
enum chan_width to common/defs.h (which was already pulled in into
src/drivers/driver.h and src/common/ieee802_11_common.h).
Signed-off-by: Jouni Malinen <jouni@codeaurora.org>