reset: Add compile-test stubs

Add stubs for the reset controller registration functions to allow
building reset controller provider drivers with the COMPILE_TEST
Kconfig option enabled.
Reported-by: NKrzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Suggested-by: NDmitry Osipenko <digetx@gmail.com>
Signed-off-by: NThierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20210609112806.3565057-3-thierry.reding@gmail.comSigned-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

include/linux/reset-controller.h

@@ -79,6 +79,7 @@ struct reset_controller_dev {
 	unsigned int nr_resets;
 };
 
+#if IS_ENABLED(CONFIG_RESET_CONTROLLER)
 int reset_controller_register(struct reset_controller_dev *rcdev);
 void reset_controller_unregister(struct reset_controller_dev *rcdev);
 
@@ -88,5 +89,26 @@ int devm_reset_controller_register(struct device *dev,
 
 void reset_controller_add_lookup(struct reset_control_lookup *lookup,
 				 unsigned int num_entries);
+#else
+static inline int reset_controller_register(struct reset_controller_dev *rcdev)
+{
+	return 0;
+}
+
+static inline void reset_controller_unregister(struct reset_controller_dev *rcdev)
+{
+}
+
+static inline int devm_reset_controller_register(struct device *dev,
+						 struct reset_controller_dev *rcdev)
+{
+	return 0;
+}
+
+static inline void reset_controller_add_lookup(struct reset_control_lookup *lookup,
+					       unsigned int num_entries)
+{
+}
+#endif
 
 #endif