PresentDisplay should return true if modeset is succesful.

PresentDisplay should return true if modeset is succesful.

If we are doing modeset or commit failed we return false in
PresentDisplay, which means we failed to update layers. While
this is correct when commit failed, this is not true when commit
passed and we are handling modeset. Right thing is to just return
the value of succesful_commit here.

Bug ID: https://01.org/jira/browse/AIA-131
Test: hwc-drm-two: Failed to set layers in the composition is not shown
      in logcat during boot up.

Signed-off-by: Carlos Santa <carlos.santa@intel.com>