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

fpga: dfl: afu: add afu sub feature support

User Accelerated Function Unit sub feature exposes the MMIO region of
the AFU. After valid PR bitstream is programmed and the port is enabled,
then this MMIO region could be accessed.

This patch adds support to enumerate the AFU MMIO region and expose it
to userspace via mmap file operation. Below interfaces are exposed to user:

Sysfs interface:
* /sys/class/fpga_region/<regionX>/<dfl-port.x>/afu_id
Read-only. Indicate which PR bitstream is programmed to this AFU.

Ioctl interfaces:
* DFL_FPGA_PORT_GET_INFO
Provide info to userspace on the number of supported region.
Only UAFU region is supported now.

* DFL_FPGA_PORT_GET_REGION_INFO
Provide region information, including access permission, region size,
offset from the start of device fd.

Signed-off-by: Tim Whisonant <tim.whisonant@intel.com>
Signed-off-by: Enno Luebbers <enno.luebbers@intel.com>
Signed-off-by: Shiva Rao <shiva.rao@intel.com>
Signed-off-by: Christopher Rauer <christopher.rauer@intel.com>
Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Wu Hao <hao.wu@intel.com>
Acked-by: Alan Tull <atull@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>