base-modem: plug memleaks when building port lists

The mm_base_modem_find_ports() method builds a list of full
references, so we need to unref them in the peek() methods.

    ==10047== 14,959 (24 direct, 14,935 indirect) bytes in 1 blocks are definitely lost in loss record 5,470 of 5,473
    ==10047==    at 0x4C2CE5F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
    ==10047==    by 0x66E3028: g_malloc (in /usr/lib/libglib-2.0.so.0.5200.3)
    ==10047==    by 0x66FAB25: g_slice_alloc (in /usr/lib/libglib-2.0.so.0.5200.3)
    ==10047==    by 0x66D9A33: g_list_append (in /usr/lib/libglib-2.0.so.0.5200.3)
    ==10047==    by 0x15F6A7: mm_base_modem_find_ports (mm-base-modem.c:845)
    ==10047==    by 0x15E9F3: mm_base_modem_peek_port_qmi_for_data (mm-base-modem.c:579)
    ==10047==    by 0x15E8FC: mm_base_modem_get_port_qmi_for_data (mm-base-modem.c:555)
    ==10047==    by 0x1BB99F: _connect (mm-bearer-qmi.c:1391)
    ==10047==    by 0x1540B4: mm_base_bearer_connect (mm-base-bearer.c:841)
    ==10047==    by 0x181F4F: connection_step (mm-iface-modem-simple.c:597)
    ==10047==    by 0x181321: create_bearer_ready (mm-iface-modem-simple.c:258)
    ==10047==    by 0x612FD52: ??? (in /usr/lib/libgio-2.0.so.0.5200.3)
1 file changed