drm/i915: Fix docbook descriptions for i915_cmd_parser

drm/i915: Fix docbook descriptions for i915_cmd_parser

Fixes the following htmldocs warnings:
drivers/gpu/drm/i915/i915_cmd_parser.c:1420: warning: Excess function parameter 'trampoline' description in 'intel_engine_cmd_parser'
drivers/gpu/drm/i915/i915_cmd_parser.c:1420: warning: Function parameter or member 'jump_whitelist' not described in 'intel_engine_cmd_parser'
drivers/gpu/drm/i915/i915_cmd_parser.c:1420: warning: Function parameter or member 'shadow_map' not described in 'intel_engine_cmd_parser'
drivers/gpu/drm/i915/i915_cmd_parser.c:1420: warning: Function parameter or member 'batch_map' not described in 'intel_engine_cmd_parser'
drivers/gpu/drm/i915/i915_cmd_parser.c:1420: warning: Excess function parameter 'trampoline' description in 'intel_engine_cmd_parser'

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210421120353.544518-1-maarten.lankhorst@linux.intel.com
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>