libmbim-glib,compat: fix return of the MbimLteAttachStatus struct

We should not free it before returning it... :)

  Thread 1 "ModemManager" received signal SIGABRT, Aborted.
  0x00007ffff7837ef5 in raise () from /usr/lib/libc.so.6
  (gdb) bt
  #0  0x00007ffff7837ef5 in raise () at /usr/lib/libc.so.6
  #1  0x00007ffff7821862 in abort () at /usr/lib/libc.so.6
  #2  0x00007ffff7879f38 in __libc_message () at /usr/lib/libc.so.6
  #3  0x00007ffff7881bea in  () at /usr/lib/libc.so.6
  #4  0x00007ffff7883113 in _int_free () at /usr/lib/libc.so.6
  #5  0x00007ffff7886ca8 in free () at /usr/lib/libc.so.6
  #6  0x0000555555616ec5 in lte_attach_status_query_ready (device=0x7fffe8007e30, res=0x7fffe8011ee0, task=0x55555574bb30) at mm-broadband-modem-mbim.c:2713
  #7  0x00007ffff7cd33d4 in  () at /usr/lib/libgio-2.0.so.0
  #8  0x00007ffff7cd77b9 in  () at /usr/lib/libgio-2.0.so.0
  #9  0x00007ffff7e26a7f in transaction_task_complete_and_free (task=0x7fffe8011ee0, error=0x0) at ../src/libmbim-glib/mbim-device.c:243
  #10 0x00007ffff7e2864d in process_message (message=<optimized out>, self=0x7fffe8007e30) at ../src/libmbim-glib/mbim-device.c:906
  #11 parse_response (self=0x7fffe8007e30) at ../src/libmbim-glib/mbim-device.c:1049
  #12 data_available (source=0x55555571ec50, condition=<optimized out>, self=0x7fffe8007e30) at ../src/libmbim-glib/mbim-device.c:1125
  #13 0x00007ffff7af5f30 in g_main_context_dispatch () at /usr/lib/libglib-2.0.so.0
  #14 0x00007ffff7b49b59 in  () at /usr/lib/libglib-2.0.so.0
  #15 0x00007ffff7af5593 in g_main_loop_run () at /usr/lib/libglib-2.0.so.0
  #16 0x000055555558402f in main (argc=2, argv=0x7fffffffead8) at main.c:210