fpga: bridge: Use standard dev_release for class driver

The FPGA bridge 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() function.

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>