Wayland: remove duplicate tracing category.

Wayland code uses "wayland" category. "Wayland" was added here
by mistake. Thus, remove it.

Bug: 578890
Change-Id: Ia8988559c6fc52177910c15a118ecd1602f21dbb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1640409Reviewed-by: Ehsan Chiniforooshan <chiniforooshan@chromium.org>
Commit-Queue: Maksim Sisov <msisov@igalia.com>
Cr-Commit-Position: refs/heads/master@{#665829}

base/trace_event/builtin_categories.h

@@ -136,7 +136,6 @@
   X("viz")                                                               \
   X("vk")                                                                \
   X("wayland")                                                           \
-  X("Wayland")                                                           \
   X("webaudio")                                                          \
   X("WebCore")                                                           \
   X("webrtc")                                                            \