soc: ti: omap-prm: use atomic iopoll instead of sleeping one

soc: ti: omap-prm: use atomic iopoll instead of sleeping one

The reset handling APIs for omap-prm can be invoked PM runtime which
runs in atomic context. For this to work properly, switch to atomic
iopoll version instead of the current which can sleep. Otherwise,
this throws a "BUG: scheduling while atomic" warning. Issue is seen
rather easily when CONFIG_PREEMPT is enabled.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Acked-by: Santosh Shilimkar <ssantosh@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>