net: mscc: ocelot: add missing lock protection in ocelot_port_xmit_inj()

net: mscc: ocelot: add missing lock protection in ocelot_port_xmit_inj()

ocelot_port_xmit_inj() calls ocelot_can_inject() and
ocelot_port_inject_frame() without holding the injection group lock.
Both functions contain lockdep_assert_held() for the injection lock,
and the correct caller felix_port_deferred_xmit() properly acquires
the lock using ocelot_lock_inj_grp() before calling these functions.

Add ocelot_lock_inj_grp()/ocelot_unlock_inj_grp() around the register
injection path to fix the missing lock protection. The FDMA path is not
affected as it uses its own locking mechanism.

Fixes: c5e12ac3beb0 ("net: mscc: ocelot: serialize access to the injection/extraction groups")
Signed-off-by: Ziyi Guo <n7l8m4@u.northwestern.edu>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20260208225602.1339325-4-n7l8m4@u.northwestern.edu
Signed-off-by: Jakub Kicinski <kuba@kernel.org>