If an DMA channel was active at suspend, then ensure that
it is correctly reconfigured when the system resumes.

Note, the previous policy was for each driver to handle their
own reconfiguration on resume. The policy has been changed to
make the individual driver's job easier.
Signed-off-by: NBen Dooks <ben-linux@flfuf.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>