ozone/linux: disable automatic compilation of ozone/drm

Change-Id: I94756241300ec1d90fdc87391ec57c2dabc7b512
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2355951Reviewed-by: Robert Kroeger <rjkroege@chromium.org>
Commit-Queue: Maksim Sisov (GMT+3) <msisov@igalia.com>
Cr-Commit-Position: refs/heads/master@{#798170}

ui/ozone/ozone.gni

@@ -76,7 +76,6 @@ declare_args() {
       ozone_platform = "x11"
       ozone_platform_wayland = true
       ozone_platform_x11 = true
-      ozone_platform_gbm = true
     } else if (is_win) {
       ozone_platform = "windows"
       ozone_platform_windows = true