net: wwan: iosm: Fix memory leak in ipc_mux_deinit()

net: wwan: iosm: Fix memory leak in ipc_mux_deinit()

Commit 1f52d7b62285 ("net: wwan: iosm: Enable M.2 7360 WWAN card support")
allocated memory for pp_qlt in ipc_mux_init() but did not free it in
ipc_mux_deinit(). This results in a memory leak when the driver is
unloaded.

Free the allocated memory in ipc_mux_deinit() to fix the leak.

Fixes: 1f52d7b62285 ("net: wwan: iosm: Enable M.2 7360 WWAN card support")
Co-developed-by: Jianhao Xu <jianhao.xu@seu.edu.cn>
Signed-off-by: Jianhao Xu <jianhao.xu@seu.edu.cn>
Signed-off-by: Zilin Guan <zilin@seu.edu.cn>
Reviewed-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
Link: https://patch.msgid.link/20251230071853.1062223-1-zilin@seu.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>