cmake/zephyr: unify cmake rules for google_hotword_detect

Adding all source files in a single, giant zephyr/CMakeLists.txt is
inconvenient and does not scale.

Modify Zephyr rules to use definitions in src/audio/google/
instead.

Link: #8260
Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>

Author: kv2019i

src/audio/google/CMakeLists.txt

@@ -10,6 +10,10 @@ if(zephyr) ###  Zephyr ###
 		set(ipc_suffix ipc4)
 	endif()
 
+	zephyr_library_sources_ifdef(CONFIG_COMP_GOOGLE_HOTWORD_DETECT
+		google_hotword_detect.c
+	)
+
 	if(CONFIG_COMP_GOOGLE_RTC_AUDIO_PROCESSING STREQUAL "m")
 		add_subdirectory(llext_rtc
 				 ${PROJECT_BINARY_DIR}/google_rtc_audio_processing_llext)

zephyr/CMakeLists.txt

@@ -548,10 +548,6 @@ elseif(CONFIG_SAMPLE_SMART_AMP)
 	)
 endif()
 
-zephyr_library_sources_ifdef(CONFIG_COMP_GOOGLE_HOTWORD_DETECT
-	${SOF_AUDIO_PATH}/google/google_hotword_detect.c
-)
-
 if(CONFIG_PROBE STREQUAL "m")
 	add_subdirectory(${SOF_SRC_PATH}/probe/llext
 			 ${PROJECT_BINARY_DIR}/probe_llext)