drm/i915/guc: Convert mapping table to iosys_map

Use iosys_map to write the fields system_info.mapping_table[][].
Since we already have the info_map around where needed, just use it
instead of going through guc->ads_map.

Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: John Harrison <John.C.Harrison@Intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220216174147.3073235-13-lucas.demarchi@intel.com