Don't fetch firmware address and recompute channel control on each
port access. Precompute the values on init and use them later all
the time.

The same for board control.

This simplify code and improves readability.
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>