drm/xe/pvc: Fix WA 18020744125

drm/xe/pvc: Fix WA 18020744125

With the current state GUC_WA_RCS_REGS_IN_CCS_REGS_LIST could in theory
be removed since there is no render register being added to the list of
compute WAs. However the real issue is that 18020744125 is incomplete
and not setting the RING_HWSTAM on render as it should.

Writing this in RTP is a little more tricky as we want to write to
another's engine base when the match happens: first compute engine and
no render present. So use RING_HWSTAM(RENDER_RING_BASE) instead of the
usual XE_RTP_ACTION_FLAG(ENGINE_BASE).

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240306192128.1895603-2-lucas.demarchi@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>