drm/i915: Remove unused 'in_vbl' from i915_get_crtc_scanoutpos()

Commit 1bf6ad6 ("drm/vblank: drop the mode argument from
drm_calc_vbltimestamp_from_scanoutpos") removed the use of in_vbl, but
did not remove the local variable. Do so now.

Fixes: 1bf6ad6 ("drm/vblank: drop the mode argument from drm_calc_vbltimestamp_from_scanoutpos")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170914164213.18461-1-chris@chris-wilson.co.uk
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

drivers/gpu/drm/i915/i915_irq.c

@@ -872,7 +872,6 @@ static bool i915_get_crtc_scanoutpos(struct drm_device *dev, unsigned int pipe,
 								pipe);
 	int position;
 	int vbl_start, vbl_end, hsync_start, htotal, vtotal;
-	bool in_vbl = true;
 	unsigned long irqflags;
 
 	if (WARN_ON(!mode->crtc_clock)) {
@@ -955,8 +954,6 @@ static bool i915_get_crtc_scanoutpos(struct drm_device *dev, unsigned int pipe,
 
 	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
 
-	in_vbl = position >= vbl_start && position < vbl_end;
-
 	/*
 	 * While in vblank, position will be negative
 	 * counting up towards 0 at vbl_end. And outside