Revert "drm/i915/dp: use VBT provided eDP params if available"

This reverts commit 869184a6

.

This is required for the Sony Vaio Jesse was working on at the time, but
breaks most other eDP machines - machines that were working in earlier
kernels.

Reported-and-tested-by: Dave Airlie <airlied@redhat.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=31188


Tested-by: Zhao Jian <jian.j.zhao@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>