ivi-shell: emit created notification earlier for desktop surfaces

Without this, the earliest signal the ivi controller receives for a new surface
is configure_desktop_changed signal. And this is not emitted until the surface
has the first buffer attached.
By emitting the signal during surface creation, the controller is able to set
the initial width and height for the first configure.

Signed-off-by: Michael Olbrich <m.olbrich@pengutronix.de>