Revert "adjust UMP_MEM_SIZE to 2048"

This reverts commit 9fbde12bbc1eb94af1dab49c5824ba69d165f57e.
Revert "mali: adjust MALI_GPU_UTILIZATION_TIMEOUT to 800"

This reverts commit 84334b8a2eebe7f231c067b8aad7cd6009994255.
 sched: Prevent wakeup to enter critical section needlessly

Check the waitqueue task list to be non empty before entering the critical
section. This prevents locking the spin lock needlessly in case the queue
was empty, and therefor also prevent scheduling overhead on a PREEMPT_RT
system.

Signed-off-by: Ivo Sieben <meltedpianoman@gmail.com>
backported from Linux 3.5+ by faux123