ui/gfx/linux: Remove 2 unnecessary preprocessor defs

This CL removes two unnecessary preprocessor definitions, that were not
there when the code landed, but now they are after the appropriate
//third_party/libdrm uprev. No new code, just a cleanup to close a bug.

Bug: 958181
Change-Id: I3e9cab3ba5677585d188c4e54676aa525224a515
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2225251
Commit-Queue: Daniel Nicoara <dnicoara@chromium.org>
Auto-Submit: Miguel Casas <mcasas@chromium.org>
Reviewed-by: Daniel Nicoara <dnicoara@chromium.org>
Cr-Commit-Position: refs/heads/master@{#774610}

ui/gfx/linux/drm_util_linux.cc

@@ -8,15 +8,6 @@
 
 #include "base/notreached.h"
 
-#ifndef DRM_FORMAT_INVALID
-// TODO(mcasas): Remove when uprevving //third_party/libdrm.
-#define DRM_FORMAT_INVALID 0
-#endif
-
-#ifndef DRM_FORMAT_P010
-#define DRM_FORMAT_P010 fourcc_code('P', '0', '1', '0')
-#endif
-
 namespace ui {
 
 int GetFourCCFormatFromBufferFormat(gfx::BufferFormat format) {