net: wwan: iosm: fix memory leak in ipc_mux_init()

When failed to alloc ipc_mux->ul_adb.pp_qlt in ipc_mux_init(), ipc_mux
is not released.

Fixes: 1f52d7b6

 ("net: wwan: iosm: Enable M.2 7360 WWAN card support")
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
Reviewed-by: M Chetan Kumar <m.chetan.kumar@intel.com>
Link: https://lore.kernel.org/r/20221203020903.383235-1-shaozhengchao@huawei.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>