octeontx2-pf: Add missing changes in otx2_ethtool.c

commit f38e38ff5fc70db2a0a33256e4387feb45bd5b67 from
git@git.assembla.com:cavium/WindRiver.linux.git

Changes related to stats, XDP and mutex lock for
pause frame message are missing and this patch adds
those.

Change-Id: I1c058e0d41d1dba3fe5cc43772633c9d43bcef4b
Signed-off-by: Subbaraya Sundeep <sbhatta@marvell.com>
Signed-off-by: Ruiqiang Hao <Ruiqiang.Hao@windriver.com>