fpga: region: Use standard dev_release for class driver

The FPGA region class driver data structure is being treated as a
managed resource instead of using the standard dev_release call-back
function to release the class data structure. This change removes the
managed resource code and combines the create() and register()
functions into a single register() or register_full() function.

The register_full() function accepts an info data structure to provide
flexibility in passing optional parameters. The register() function
supports the current parameter list for users that don't require the
use of optional parameters.

Signed-off-by: Russ Weight <russell.h.weight@intel.com>
Reviewed-by: Xu Yilun <yilun.xu@intel.com>
Acked-by: Xu Yilun <yilun.xu@intel.com>
Signed-off-by: Moritz Fischer <mdf@kernel.org>