fpga: tests: use KUnit devices instead of platform devices

fpga: tests: use KUnit devices instead of platform devices

KUnit now provides helper functions to create fake devices, so use them
instead of relying on platform devices.

Other changes: remove an unnecessary white space in the fpga region suite.

Reviewed-by: Russ Weight <[email protected]>
Signed-off-by: Marco Pagani <[email protected]>
Acked-by: Xu Yilun <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Xu Yilun <[email protected]>