drm/i915: s/dpio_lock/sb_lock/

Rename dpio_lock to sb_lock to inform the reader that its primary
purpose is to protect the sideband mailbox rather than some DPIO
state.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
index 5196642..b5a5558 100644
--- a/drivers/gpu/drm/i915/intel_dsi.c
+++ b/drivers/gpu/drm/i915/intel_dsi.c
@@ -239,7 +239,7 @@
 
 static void band_gap_reset(struct drm_i915_private *dev_priv)
 {
-	mutex_lock(&dev_priv->dpio_lock);
+	mutex_lock(&dev_priv->sb_lock);
 
 	vlv_flisdsi_write(dev_priv, 0x08, 0x0001);
 	vlv_flisdsi_write(dev_priv, 0x0F, 0x0005);
@@ -248,7 +248,7 @@
 	vlv_flisdsi_write(dev_priv, 0x0F, 0x0000);
 	vlv_flisdsi_write(dev_priv, 0x08, 0x0000);
 
-	mutex_unlock(&dev_priv->dpio_lock);
+	mutex_unlock(&dev_priv->sb_lock);
 }
 
 static inline bool is_vid_mode(struct intel_dsi *intel_dsi)
@@ -346,11 +346,11 @@
 
 	DRM_DEBUG_KMS("\n");
 
-	mutex_lock(&dev_priv->dpio_lock);
+	mutex_lock(&dev_priv->sb_lock);
 	/* program rcomp for compliance, reduce from 50 ohms to 45 ohms
 	 * needed everytime after power gate */
 	vlv_flisdsi_write(dev_priv, 0x04, 0x0004);
-	mutex_unlock(&dev_priv->dpio_lock);
+	mutex_unlock(&dev_priv->sb_lock);
 
 	/* bandgap reset is needed after everytime we do power gate */
 	band_gap_reset(dev_priv);