Fix const in memcpy_by_audio_format parameter

Change-Id: I7bdeb587e45695e6a914918ba75f102048b2e0eb
diff --git a/audio_utils/format.c b/audio_utils/format.c
index caa354a..e91e057 100644
--- a/audio_utils/format.c
+++ b/audio_utils/format.c
@@ -22,7 +22,7 @@
 #include <audio_utils/format.h>
 
 void memcpy_by_audio_format(void *dst, audio_format_t dst_format,
-        void *src, audio_format_t src_format, size_t count)
+        const void *src, audio_format_t src_format, size_t count)
 {
     /* default cases for error falls through to fatal log below. */
     if (dst_format == src_format) {