drm/debugfs: add descriptions to struct parameters

The structs drm_debugfs_info and drm_debugfs_entry don't have
descriptions for their parameters, which is causing the following warnings:

include/drm/drm_debugfs.h:93: warning: Function parameter or member
'name' not described in 'drm_debugfs_info'
include/drm/drm_debugfs.h:93: warning: Function parameter or member
'show' not described in 'drm_debugfs_info'
include/drm/drm_debugfs.h:93: warning: Function parameter or member
'driver_features' not described in 'drm_debugfs_info'
include/drm/drm_debugfs.h:93: warning: Function parameter or member
'data' not described in 'drm_debugfs_info'
include/drm/drm_debugfs.h:105: warning: Function parameter or member
'dev' not described in 'drm_debugfs_entry'
include/drm/drm_debugfs.h:105: warning: Function parameter or member
'file' not described in 'drm_debugfs_entry'
include/drm/drm_debugfs.h:105: warning: Function parameter or member
'list' not described in 'drm_debugfs_entry'

Therefore, fix the warnings by adding descriptions to all struct
parameters.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Maíra Canal <mcanal@igalia.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Maíra Canal <mairacanal@riseup.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20230105193039.287677-2-mcanal@igalia.com