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

In the Linux kernel, the following vulnerability has been resolved:

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.