fpga: dfl: more kernel-doc corrections

Fix more kernel-doc warnings in drivers/fpga/:

$ ./scripts/kernel-doc -none drivers/fpga/*
drivers/fpga/dfl-afu.h:61: warning: expecting prototype for struct fpga_afu_dma_region. Prototype was for struct dfl_afu_dma_region instead
drivers/fpga/dfl-afu-region.c:52: warning: Function parameter or member 'pdata' not described in 'afu_mmio_region_add'
drivers/fpga/dfl-fme-perf.c:161: warning: Function parameter or member 'node' not described in 'fme_perf_priv'
drivers/fpga/dfl-fme-pr.h:70: warning: expecting prototype for struct dfl_fme_bridge_pdata. Prototype was for struct dfl_fme_br_pdata instead
drivers/fpga/dfl.h:256: warning: Function parameter or member 'revision' not described in 'dfl_feature'

Signed-off-by: Xu Yilun <yilun.xu@intel.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20230114155444.794712-1-yilun.xu@intel.com