Fix return type to be void.

Missing return type causes warning (which is treated as an error) when
compiling with Clang.

BUG=chromium:539781
R=rtoy@google.com

Review URL: https://codereview.webrtc.org/1578463002 .
diff --git a/dl/sp/src/arm/arm64/omxSP_FFTInv_CCSToR_F32.c b/dl/sp/src/arm/arm64/omxSP_FFTInv_CCSToR_F32.c
index 84de9cf..771c671 100644
--- a/dl/sp/src/arm/arm64/omxSP_FFTInv_CCSToR_F32.c
+++ b/dl/sp/src/arm/arm64/omxSP_FFTInv_CCSToR_F32.c
@@ -72,7 +72,7 @@
 /*
  * Scale FFT data by 1/|length|. |length| must be a power of two
  */
-static inline ScaleRFFTData(OMX_F32* fftData, unsigned length) {
+static inline void ScaleRFFTData(OMX_F32* fftData, unsigned length) {
   float32_t* data = (float32_t*)fftData;
   float32_t scale = 2.0f / length;
 
diff --git a/dl/sp/src/arm/arm64/omxSP_FFTInv_CToC_FC32.c b/dl/sp/src/arm/arm64/omxSP_FFTInv_CToC_FC32.c
index eec05e9..b767a0a 100644
--- a/dl/sp/src/arm/arm64/omxSP_FFTInv_CToC_FC32.c
+++ b/dl/sp/src/arm/arm64/omxSP_FFTInv_CToC_FC32.c
@@ -66,7 +66,7 @@
 /*
  * Scale FFT data by 1/|length|. |length| must be a power of two
  */
-static inline ScaleFFTData(OMX_FC32* fftData, unsigned length) {
+static inline void ScaleFFTData(OMX_FC32* fftData, unsigned length) {
   float32_t* data = (float32_t*)fftData;
   float32_t scale = 1.0f / length;