staging: r8188eu: use in-kernel ieee80211 header structures

The structures

rtw_ieee80211_hdr
rtw_ieee80211_hdr_3addr
rtw_ieee80211_hdr_3addr_qos

in drivers/staging/r8188eu/include/ieee80211.h just duplicate the
in-kernel structures from include/linux/ieee80211.h.

ieee80211_hdr
ieee80211_hdr_3addr
ieee80211_qos_hdr

Remove the rtw_ prefixed structures and use the in-kernel versions.

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20220418180916.11311-1-straube.linux@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>