drm/i915: do not ignore eDP bpc settings from vbt

drm/i915: do not ignore eDP bpc settings from vbt

There are laptops out there that need the eDP bpc from VBT. This is
effectively a revert of

commit 147136a860e65b48280ee8625bbe0e87247032ce
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Fri Aug 10 11:10:20 2012 +0200

    drm/i915: ignore eDP bpc settings from vbt

but putting the VBT check after the EDID check to see them both in dmesg if
this clamps more than the EDID. We have enough history with bpc clamping to
warrant the extra debug info.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=47641
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=56401
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>