net: wwan: iosm: Call mutex_init before locking it

wwan_register_ops calls wwan_create_default_link, which ends up in the
ipc_wwan_newlink callback that locks ipc_wwan->if_mutex. However, this
mutex is not yet initialized by that point. Fix it by moving mutex_init
above the wwan_register_ops call. This also makes the order of
operations in ipc_wwan_init symmetric to ipc_wwan_deinit.

Fixes: 83068395 ("net: iosm: create default link via WWAN core")
Signed-off-by: Maxim Mikityanskiy <maxtram95@gmail.com>
Reviewed-by: M Chetan Kumar <m.chetan.kumar@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>