drm/dp/mst: update the link_address_sent before sending the link address (v3)

Update the state before sending the msg to close it.

v2: reset value if return indicates we haven't send the msg.
v3: just clean the code up.
Pointed out by Adam J Richter on

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91481



Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>