drm/i915: remove i915_disable_vga_mem declaration

It was supposed to have been killed on the same commit that killed the
function, e1264ebe9ff48e1b3e1dd11805eec9f5b143ab7c, but I guess the
intel_drv.h reorganization accidentally brought it back.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_drv.h

@@ -703,7 +703,6 @@ void
 ironlake_check_encoder_dotclock(const struct intel_crtc_config *pipe_config,
 				int dotclock);
 bool intel_crtc_active(struct drm_crtc *crtc);
-void i915_disable_vga_mem(struct drm_device *dev);
 void hsw_enable_ips(struct intel_crtc *crtc);
 void hsw_disable_ips(struct intel_crtc *crtc);
 void intel_display_set_init_power(struct drm_device *dev, bool enable);