dm: fpga: Introduce new uclass

For future DM based FPGA drivers and for now to have a meaningful
logging class for old FPGA drivers.

Suggested-by: Michal Simek <michal.simek@amd.com>
Suggested-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Alexander Dahl <post@lespocky.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Link: https://lore.kernel.org/r/20220930120430.42307-2-post@lespocky.de
Signed-off-by: Michal Simek <michal.simek@amd.com>

MAINTAINERS

@@ -945,6 +945,7 @@ T:	git https://source.denx.de/u-boot/custodians/u-boot-microblaze.git
 F:	drivers/fpga/
 F:	cmd/fpga.c
 F:	include/fpga.h
+F:	test/dm/fpga.c
 
 FLATTENED DEVICE TREE
 M:	Simon Glass <sjg@chromium.org>