drm/i915: change VLV IOSF sideband accessors to not return error code

We never check the return values, and there's not much we could do on
errors anyway. Just simplify the signatures. No functional changes.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 28d14d6..f6419f4 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1931,9 +1931,9 @@
 int sandybridge_pcode_write(struct drm_i915_private *dev_priv, u8 mbox, u32 val);
 
 /* intel_sideband.c */
-int vlv_punit_read(struct drm_i915_private *dev_priv, u8 addr, u32 *val);
-int vlv_punit_write(struct drm_i915_private *dev_priv, u8 addr, u32 val);
-int vlv_nc_read(struct drm_i915_private *dev_priv, u8 addr, u32 *val);
+u32 vlv_punit_read(struct drm_i915_private *dev_priv, u8 addr);
+void vlv_punit_write(struct drm_i915_private *dev_priv, u8 addr, u32 val);
+u32 vlv_nc_read(struct drm_i915_private *dev_priv, u8 addr);
 u32 vlv_dpio_read(struct drm_i915_private *dev_priv, int reg);
 void vlv_dpio_write(struct drm_i915_private *dev_priv, int reg, u32 val);
 u32 intel_sbi_read(struct drm_i915_private *dev_priv, u16 reg,