drm/i915: Polish intel_get_lvds_encoder()

Pass dev_priv to intel_get_lvds_encoder() and polish the
implementation a bit.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190318202653.15217-2-ville.syrjala@linux.intel.com
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/i915/intel_drv.h

@@ -2116,7 +2116,7 @@ void intel_read_infoframe(struct intel_encoder *encoder,
 bool intel_lvds_port_enabled(struct drm_i915_private *dev_priv,
 			     i915_reg_t lvds_reg, enum pipe *pipe);
 void intel_lvds_init(struct drm_i915_private *dev_priv);
-struct intel_encoder *intel_get_lvds_encoder(struct drm_device *dev);
+struct intel_encoder *intel_get_lvds_encoder(struct drm_i915_private *dev_priv);
 bool intel_is_dual_link_lvds(struct drm_device *dev);
 
 /* intel_overlay.c */