drm/i915: remove Pineview EOS protection support

drm/i915: remove Pineview EOS protection support

HW guys have an evaluation about the impact about EOS, and say the impact
is quite small, so they have removed EOS detection support. This patch
removes EOS feature.

revert commit 6892f6e483c3fcbe378608f4bed369b0261e396c
directly reverting it gives a hunk error, so please use this one.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
[anholt: fixed up commit message for update that the feature's really gone]