drm/i915: don't wait for vblank after enabling pipe on HSW

drm/i915: don't wait for vblank after enabling pipe on HSW

Because on Haswell, the pipe is never running at this point, so we hit
the 50ms timeout waiting for nothing. We already have two other places
where we wait for vblanks on haswell_crtc_enable, so we're safe.

This gets us rid of one instance of "vblank wait timed out" for each
mode set, which means driver init and resume are also 50ms faster.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>