MFC r312884

sfxge(4): fix RxQ structure layout vs usage on datapath

Recent changes in the pseudo header accessor prototypes start to
use common code RxQ handle on datapath. The handle was located
at the end of the structure with members not used on datapath.

Sponsored by: Solarflare Communications, Inc.
Differential Revision: https://reviews.freebsd.org/D9359