drm/xe: Fix ring flush invalidation

Emit_flush_invalidate() is incorrectly marking the write to LRC_PPHWSP as
a GGTT write and also writing an atypical ~0 dword as the payload. Fix it.

While at it drop the unused flags argument.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250307111402.26577-3-tvrtko.ursulin@igalia.com


Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
(cherry picked from commit 08ea901d)
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>