drm/vblank: limit vblank variable scope to atomic

In drm_crtc_vblank_helper_get_vblank_timestamp_internal(), we only need
the vblank variable for atomic modesetting. Limit the scope to make
upcoming changes easier.

Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patch.msgid.link/b50f0bff654a6902ffd7ae52c31d46fad9ed7540.1765290097.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

Author: jnikula

drivers/gpu/drm/drm_vblank.c

@@ -710,7 +710,6 @@ drm_crtc_vblank_helper_get_vblank_timestamp_internal(
 {
 	struct drm_device *dev = crtc->dev;
 	unsigned int pipe = crtc->index;
-	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
 	struct timespec64 ts_etime, ts_vblank_time;
 	ktime_t stime, etime;
 	bool vbl_status;
@@ -729,10 +728,13 @@ drm_crtc_vblank_helper_get_vblank_timestamp_internal(
 		return false;
 	}
 
-	if (drm_drv_uses_atomic_modeset(dev))
+	if (drm_drv_uses_atomic_modeset(dev)) {
+		struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
+
 		mode = &vblank->hwmode;
-	else
+	} else {
 		mode = &crtc->hwmode;
+	}
 
 	/* If mode timing undefined, just return as no-op:
 	 * Happens during initial modesetting of a crtc.