Use iflib_if_init_locked() during media change instead of iflib_init_locked().

iflib_init_locked() assumes that iflib_stop() has been called, however,
it is not called for media changes.
iflib_if_init_locked() calls stop then init, so fixes the problem.

PR: 253473
Sponsored by: Juniper Networks, Inc., Klara, Inc.
Approved by: re (gjb)

(cherry picked from commit 922cf8ac43adc9983f9a9e05cfd838306c1ef483)