drm/i915: add support for dvo Chrontel 7010B

This patch add dvo detection for the Chrontel 7010B on some old hardware.

References: https://bugzilla.kernel.org/show_bug.cgi?id=55101


Signed-off-by: Braggle <braggle at free.fr>
[danvet: Fix up whitespace mangling.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>