OMAP: hwmod: add non-locking versions of enable and idle functions

Some hwmods may need to be idled/enabled in atomic context, so
non-locking versions of these functions are required.

Most users should not need these and usage of theses should be
controlled to understand why access is being done in atomic context.
For this reason, the non-locking functions are only exposed at the
hwmod level and not at the omap-device level.

The use-case that led to the need for the non-locking versions is
hwmods that are enabled/idled from within the core idle/suspend path.
Since interrupts are already disabled here, the mutex-based locking in
hwmod can sleep and will cause potential deadlocks.

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