staging: r8188eu: remove ETH_ALEN from ieee80211.h

The definition of ETH_ALEN in ieee80211.h is redundant as it is an
in-kernel constant. Remove it.

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20220225120843.10674-5-straube.linux@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>