drm/panel: otm8009a: No message if probe success

Remove the message in case of probe success. This comes from a
suggestion followed in the recent integration of the raydium rm68200
panel.

Signed-off-by: Philippe Cornu <philippe.cornu@st.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180423141054.13128-4-philippe.cornu@st.com