mali: mark kbase_pm workqueue WQ_MEM_RECLAIM

kbase_cpu_vm_close, which is run in reclaim if the oom killer fires,
waits on the kbase_pm worker.  Mark the kbase_pm worker WQ_MEM_RECLAIM
to make sure it can always run during reclaim, even if there is not
enough memory to spawn new kworkers.

Change-Id: Idf9df2bbf4c70533dc54de31dbe0419ba995eddd
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>