drm/i915: ignore eDP bpc settings from vbt

drm/i915: ignore eDP bpc settings from vbt

This has originally been introduced to not oversubscribe the dp links
in

commit 0f88e12a36492e49a746267d28cc443420f059f1
Author: Zhenyu Wang <zhenyuw@linux.intel.com>
Date:   Tue Jan 12 05:38:31 2010 +0800

    drm/i915: fix pixel color depth setting on eDP

Since then we've fixed up the dp link bandwidth calculation code and
should now automatically fall back to 6bpc dithering. So this is
unnecessary.

Furthermore it seems to break the new MacbookPro with retina display,
hence let's just rip this out.

Reported-by: Benoit Gschwind <gschwind@gnu-log.net>
Cc: Benoit Gschwind <gschwind@gnu-log.net>
Cc: Francois Rigaut <frigaut@gmail.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: stable@vger.kernel.org
Tested-by: Benoit Gschwind <gschwind@gnu-log.net>
Tested-by: Bernhard Froemel <froemel at vmars tuwien.ac.at>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
--

Testing feedback highgly welcome, and thanks for Benoit for finding
out that the bpc computations are busted.
-Daniel