OMAP: powerdomain: remove omap_chip bitmasks

At Tony's request, remove the omap_chip bitmasks from the powerdomain
definitions.  Instead, initialize powerdomains based on one or more
lists that are applicable to a particular SoC family, variant, and
silicon revision.

Gražvydas Ignotas <notasas@gmail.com> found and reported a bug in a
related patch that also applied to this patch - thanks Gražvydas.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Gražvydas Ignotas <notasas@gmail.com>