drm/i915: remove comment about HSW HDMI DIPs

HSW support is now just like all the other generations: we send AVI
and SPD InfoFrames. There are other DIPs for HSW, but there are other
DIPs for the previous generations too. For each gen, we can see which
DIPs are missing by looking at the 'set_infoframes' function: we
explicitly disable the DIPs we're not using.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>