Small cleanup of Util constants.

- Remove null checks (never happens).
- Use "const".equals(Util.CONST) where possible.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=128351654

library/src/main/java/com/google/android/exoplayer2/mediacodec/MediaCodecRenderer.java

@@ -1018,8 +1018,8 @@ public abstract class MediaCodecRenderer extends BaseRenderer {
   private static boolean codecNeedsAdaptationWorkaround(String name) {
     return Util.SDK_INT < 24
         && ("OMX.Nvidia.h264.decode".equals(name) || "OMX.Nvidia.h264.decode.secure".equals(name))
-        && (Util.DEVICE.equals("flounder") || Util.DEVICE.equals("flounder_lte")
-            || Util.DEVICE.equals("grouper") || Util.DEVICE.equals("tilapia"));
+        && ("flounder".equals(Util.DEVICE) || "flounder_lte".equals(Util.DEVICE)
+            || "grouper".equals(Util.DEVICE) || "tilapia".equals(Util.DEVICE));
   }
 
   /**

library/src/main/java/com/google/android/exoplayer2/mediacodec/MediaCodecUtil.java

@@ -258,14 +258,14 @@ public final class MediaCodecUtil {
 
     // Work around https://github.com/google/ExoPlayer/issues/548
     // VP8 decoder on Samsung Galaxy S3/S4/S4 Mini/Tab 3 does not render video.
-    if (Util.SDK_INT <= 19 && Util.DEVICE != null
+    if (Util.SDK_INT <= 19
         && (Util.DEVICE.startsWith("d2") || Util.DEVICE.startsWith("serrano")
         || Util.DEVICE.startsWith("jflte") || Util.DEVICE.startsWith("santos"))
-        && "samsung".equals(Util.MANUFACTURER) && name.equals("OMX.SEC.vp8.dec")) {
+        && "samsung".equals(Util.MANUFACTURER) && "OMX.SEC.vp8.dec".equals(name)) {
       return false;
     }
     // VP8 decoder on Samsung Galaxy S4 cannot be queried.
-    if (Util.SDK_INT <= 19 && Util.DEVICE != null && Util.DEVICE.startsWith("jflte")
+    if (Util.SDK_INT <= 19 && Util.DEVICE.startsWith("jflte")
         && "OMX.qcom.video.decoder.vp8".equals(name)) {
       return false;
     }