OMAP2/3: WKUP powerdomain: mark as being always on

Mark the WKUP powerdomain as being always on -- at least, as long as the
chip has power.  This will be used to enable the powerdomain code to
determine whether a given powerdomain is ever able to power off.  While
here, update the file copyright.

Signed-off-by: Paul Walmsley <paul@pwsan.com>