OMAP1: PM: add simple runtime PM layer to manage clocks

On OMAP1, we do not have omap_device + omap_hwmod to manage the
device-specific idle, enable and shutdown.  Instead, just
enable/disable device clocks automatically at the runtime PM level.

This allows drivers to not have any OMAP1 specific clock management
and allows them to simply use the runtime PM API to manage clocks.

OMAP1 compile fixes Manjunatha GK <manjugk@ti.com>

Cc: Manjunatha GK <manjugk@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>