OMAP2+: clockdomains: split the clkdm hwsup enable/disable function

Split _omap2_clkdm_set_hwsup() into _disable_hwsup() and _enable_hwsup().

While here, also document that the autodeps are deprecated and that they
should be removed at the earliest opportunity.

The documentation has been fixed for _{enable,disable}_hwsup(), thanks
to Kevin Hilman <khilman@deeprootsystems.com> for pointing out that those
functions still had placeholder documentation in an earlier patch revision.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: Rajendra Nayak <rnayak@ti.com>