ARM: OMAP: omap_device: idle devices with no driver bound

Under some circumstances, drivers may leave an omap_device enabled due
to driver programming errors, or due to a failure in the drivers
probe method.

Using the recently added omap_device driver_status field, we can
detect conditions where an omap_device is enabled but has no driver
bound and then ensure that the device is properly idled until it can
be probed again.

The goal of this feature is not only to detect and warn on these error
conditions, but also to ensure that devices are properly put in
low-power states so they do not prevent SoC-wide low-power states.

Reviewed-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>