obexd: Remove unused source/header files for dbus

obexd: Remove unused source/header files for dbus

Due to using g_dbus_emit_property_changed() and g_dbus_get_properties(),
obex_dbus_signal_property_changed() is unused since commit 96063756
("obex-client: Rename org.bluez.obex.Transfer to Transfer1"), and
OBC_PROPERTIES_ARRAY_SIGNATURE macro is unused since commit 3eadc034
("obex-client: Make use of g_dbus_get_properties to get transfer properties").

Change-Id: If237f40dea006c9b96e16dc3e446dff80e591aed
Signed-off-by: Amit Purwar <amit.purwar@samsung.com>