drm/i915: Support for ns2501-DVO

This patch adds support for the ns2501 DVO, found in some older Fujitsu/Siemens Labtops.
It is in the state of "works for me".
Includes now proper DPMS support. Includes switching between resolutions -
from 640x480 to 1024x768.
Currently assumes that the native display resolution is 1024x768.

The ns2501 seems to be rather critical - if the output PLL is not
running, the chip doesn't seem to be clocked and then doesn't react
on i2c messages. Thus, a quick'n-dirty trick ensures that the DVO
is active before submitting any i2c messages to it. This is
probably to be reviewed.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=17902
Signed-off-by: Thomas Richter <thor@math.tu-berlin.de>
[danvet: fixup whitespace fail.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/dvo.h b/drivers/gpu/drm/i915/dvo.h
index 5891469..0c8ac4d 100644
--- a/drivers/gpu/drm/i915/dvo.h
+++ b/drivers/gpu/drm/i915/dvo.h
@@ -140,5 +140,6 @@
 extern struct intel_dvo_dev_ops ivch_ops;
 extern struct intel_dvo_dev_ops tfp410_ops;
 extern struct intel_dvo_dev_ops ch7017_ops;
+extern struct intel_dvo_dev_ops ns2501_ops;
 
 #endif /* _INTEL_DVO_H */