dbus: Fix memory leak with Bonjour params for a P2P UPnP service

dbus: Fix memory leak with Bonjour params for a P2P UPnP service

Using D-Bus, it is possible to add a valid UPnP service where 'query'
and 'response' are specified. In this case, memory for 'query' and
'response' is allocated but not used nor freed. Valgrind complains as
follows:

 42 bytes in 1 blocks are definitely lost in loss record 32 of 75
    at 0x484C214: calloc (vg_replace_malloc.c:1675)
    by 0x41C673: wpabuf_alloc (wpabuf.c:124)
    by 0x41C673: wpabuf_alloc_copy (wpabuf.c:162)
    by 0x54F41A: wpas_dbus_handler_p2p_add_service (dbus_new_handlers_p2p.c:2762)
    by 0x53B9A2: msg_method_handler (dbus_new_helpers.c:356)
    by 0x53B9A2: message_handler (dbus_new_helpers.c:412)
    by 0x4EAB4B8: dbus_connection_dispatch (in /usr/lib64/libdbus-1.so.3.19.13)
    by 0x5495DF: dispatch_data (dbus_common.c:37)
    by 0x5495DF: process_watch (dbus_common.c:73)
    by 0x5495DF: process_watch_read (dbus_common.c:89)
    by 0x41EE8E: eloop_sock_table_dispatch.part.0 (eloop.c:603)
    by 0x41FA46: eloop_sock_table_dispatch (eloop.c:597)
    by 0x41FA46: eloop_run (eloop.c:1233)
    by 0x56A3CE: wpa_supplicant_run (wpa_supplicant.c:8074)
    by 0x40DB06: main (main.c:393)

 49 bytes in 1 blocks are definitely lost in loss record 37 of 75
    at 0x484C214: calloc (vg_replace_malloc.c:1675)
    by 0x41C673: wpabuf_alloc (wpabuf.c:124)
    by 0x41C673: wpabuf_alloc_copy (wpabuf.c:162)
    by 0x54F348: wpas_dbus_handler_p2p_add_service (dbus_new_handlers_p2p.c:2755)
    by 0x53B9A2: msg_method_handler (dbus_new_helpers.c:356)
    by 0x53B9A2: message_handler (dbus_new_helpers.c:412)
    by 0x4EAB4B8: dbus_connection_dispatch (in /usr/lib64/libdbus-1.so.3.19.13)
    by 0x5495DF: dispatch_data (dbus_common.c:37)
    by 0x5495DF: process_watch (dbus_common.c:73)
    by 0x5495DF: process_watch_read (dbus_common.c:89)
    by 0x41EE8E: eloop_sock_table_dispatch.part.0 (eloop.c:603)
    by 0x41FA46: eloop_sock_table_dispatch (eloop.c:597)
    by 0x41FA46: eloop_run (eloop.c:1233)
    by 0x56A3CE: wpa_supplicant_run (wpa_supplicant.c:8074)
    by 0x40DB06: main (main.c:393)

Fix this ensuring that query and resp are freed both in the error and
non-error path of wpas_dbus_handler_p2p_add_service(). Also, add a test
in test_dbus.py to verify the correct behavior.

Signed-off-by: Davide Caratti <davide.caratti@gmail.com>