drm/xe/mocs: LNCF MOCS settings only need to be restored on pre-Xe_HP

Reprogramming the LNCF MOCS registers on render domain reset is not
intended to be regular driver programming, but rather the implementation
of a specific workaround (Wa_1607983814).  This workaround no longer
applies on Xe_HP any beyond, so we can expect that these registers, like
the rest of the LNCF/LBCF registers, will maintain their values through
all engine resets.  We should only add these registers to the GuC's
save/restore list on platforms that need the workaround.

Furthermore, xe_mocs_init_engine() appears to be another attempt to
satisfy this same workaround.  This is unnecessary on the Xe driver
since even on platforms where the workaround is necessary, all
single-engine resets are initiated by the GuC and thus the GuC will take
care of saving/restoring these registers.  The only host-initiated
resets we have in Xe are full GT resets which will already
(re)initialize these registers as part of the regular xe_mocs_init()
flow.

v2:
 - Add needs_wa_1607983814() so that calculate_regset_size() doesn't
   overallocate regset space when the workaround isn't needed.  (Lucas)
 - On platforms affected by Wa_1607983814, only add the LNCF MOCS
   registers to the render engine's GuC save/restore list; resets of
   other engines don't need to save/restore these.

Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>