cmake: fix CMake build break

Signed-off-by: chao an <anchao@xiaomi.com>

drivers/power/relay/CMakeLists.txt

@@ -0,0 +1,33 @@
+# ##############################################################################
+# drivers/power/relay/CMakeLists.txt
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more contributor
+# license agreements.  See the NOTICE file distributed with this work for
+# additional information regarding copyright ownership.  The ASF licenses this
+# file to you under the Apache License, Version 2.0 (the "License"); you may not
+# use this file except in compliance with the License.  You may obtain a copy of
+# the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+# License for the specific language governing permissions and limitations under
+# the License.
+#
+# ##############################################################################
+
+# Include power management sources
+
+set(SRCS)
+
+if(CONFIG_RELAY)
+  list(APPEND SRCS relay.c)
+endif()
+
+if(CONFIG_RELAY_GPIO)
+  list(APPEND SRCS relay_gpio.c)
+endif()
+
+target_sources(drivers PRIVATE ${SRCS})