Fixes a bunch of 16-bit issues that the C5X compiler warns about
diff --git a/silk/dec_API.c b/silk/dec_API.c
index 8c9ed24..77ea5e7 100644
--- a/silk/dec_API.c
+++ b/silk/dec_API.c
@@ -151,7 +151,7 @@
     psDec->nChannelsAPI      = decControl->nChannelsAPI;
     psDec->nChannelsInternal = decControl->nChannelsInternal;
 
-    if( decControl->API_sampleRate > MAX_API_FS_KHZ * 1000 || decControl->API_sampleRate < 8000 ) {
+    if( decControl->API_sampleRate > (opus_int32)MAX_API_FS_KHZ * 1000 || decControl->API_sampleRate < 8000 ) {
         ret = SILK_DEC_INVALID_SAMPLING_FREQUENCY;
         return( ret );
     }