fpga: region: Rename dev to parent for parent device

Rename variable "dev" to "parent" in cases where it represents the parent
device.

Signed-off-by: Russ Weight <russell.h.weight@intel.com>
Reviewed-by: Xu Yilun <yilun.xu@intel.com>
Signed-off-by: Moritz Fischer <mdf@kernel.org>
Link: https://lore.kernel.org/r/20210614170909.232415-6-mdf@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>