drm/i915: Rewrite ns2501 driver a bit

Try to use the same programming sequence as used by the IEGD driver.

Also shovel the magic register values into a big static const array.

The register values are actually the based on what the BIOS programs
on the Fujitsu-Siemens Lifebook S6010. IEGD seemed to have hardcoded
register values (which also enabled the scaler for 1024x768 mode).
However those didn't actually work so well on the S6010. Possibly the
pipe timings that got used didn't match the ns2501 configuration.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Thomas Richter <richter@rus.uni-stuttgart.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>