ion: Use kthread_run for ion heap pool kworker threads

Ion heap pools are refilled by kworker threads when pool
count reaches low mark, these threads are created using
kthread_create, as a result these threads will remain in
TASK_UNINTERRUPTIBLE state until they are woken up i.e; till
low mark is reached. This can result in false hung task reports.
So, fix this by replacing kthread_create with kthread_run so
that these threads get woken up just after they are created.

Change-Id: I3f96387c8a1707e917cbdc2d74b0a64ca6c6cb2f
Signed-off-by: Vijayanand Jitta <vjitta@codeaurora.org>