Remove always-true DCHECK entries that fail build when dcheck_always_on=false.

webrtc/modules/audio_coding/neteq/dtmf_tone_generator.cc

Index: webrtc/modules/audio_coding/neteq/dtmf_tone_generator.cc
diff --git a/webrtc/modules/audio_coding/neteq/dtmf_tone_generator.cc b/webrtc/modules/audio_coding/neteq/dtmf_tone_generator.cc
index 9dad2e5efd878c0242cd5f164762f6b5a4e39c73..d96bb553c08baa556f6d8b5e39944a8fdb446448 100644
--- a/webrtc/modules/audio_coding/neteq/dtmf_tone_generator.cc
+++ b/webrtc/modules/audio_coding/neteq/dtmf_tone_generator.cc
@@ -134,7 +134,6 @@ int DtmfToneGenerator::Init(int fs, int event, int attenuation) {
   }
 
   // Look up oscillator coefficient for low and high frequencies.
-  RTC_DCHECK_LE(0u, fs_index);
   RTC_DCHECK_GT(arraysize(kCoeff1), fs_index);
   RTC_DCHECK_GT(arraysize(kCoeff2), fs_index);
   RTC_DCHECK_LE(0, event);
@@ -149,7 +148,6 @@ int DtmfToneGenerator::Init(int fs, int event, int attenuation) {
   amplitude_ = kAmplitude[attenuation];
 
   // Initialize sample history.
-  RTC_DCHECK_LE(0u, fs_index);
   RTC_DCHECK_GT(arraysize(kInitValue1), fs_index);
   RTC_DCHECK_GT(arraysize(kInitValue2), fs_index);
   RTC_DCHECK_LE(0, event);