Using regmap for paging significantly improves caching since the regmap
cache no longer needs to be cleared after changing the page, so let's
use it.
Suggested-by: Armin Wolf <W_Armin@gmx.de>
Tested-by: Armin Wolf <W_Armin@gmx.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>