ARM: OMAP2+: Fix ssi hwmod entry to allow idling

The current entry prevents system from idling if
the hwmod is defined in the .dts file so let's
change the idlemodes.

Note that we probably don't have SYSC_HAS_EMUFREE
or SYSS_HAS_RESET_STATUS either. If we do, those
can be added later on.

Acked-by: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>