Disable CONFIG_RT_GROUP_SCHED

Disable CONFIG_RT_GROUP_SCHED since Android doesn't use this
feature anymore.

BUG=b:243811486
TEST=Run android-sh -c "ls /dev/cpuctl/cpu.rt_*", and ls returns
   "No such file or directory" error.

Signed-off-by: Masami Hiramatsu <mhiramat@google.com>
Change-Id: I0420bc878c92ae4625c71474688c4393b96d99cc
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/3865571


Commit-Queue: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Suleiman Souhlal <suleiman@chromium.org>
Signed-off-by: Richard Fung <richardfung@google.com>