drm/i915/display: add I915 conditional build to intel_sdvo.h

Add stubs for !I915.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Acked-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/c34ea1f470590488acf40512da3892ca153f482a.1694514689.git.jani.nikula@intel.com

drivers/gpu/drm/i915/display/intel_sdvo.h

@@ -14,9 +14,22 @@ struct drm_i915_private;
 enum pipe;
 enum port;
 
+#ifdef I915
 bool intel_sdvo_port_enabled(struct drm_i915_private *dev_priv,
 			     i915_reg_t sdvo_reg, enum pipe *pipe);
 bool intel_sdvo_init(struct drm_i915_private *dev_priv,
 		     i915_reg_t reg, enum port port);
+#else
+static inline bool intel_sdvo_port_enabled(struct drm_i915_private *dev_priv,
+					   i915_reg_t sdvo_reg, enum pipe *pipe)
+{
+	return false;
+}
+static inline bool intel_sdvo_init(struct drm_i915_private *dev_priv,
+				   i915_reg_t reg, enum port port)
+{
+	return false;
+}
+#endif
 
 #endif /* __INTEL_SDVO_H__ */