drm/i915/mtl: Update workaround 14018575942

drm/i915/mtl: Update workaround 14018575942

The WA should be extended to cover VDBOX engine. We found that
28-channels 1080p VP9 encoding may hit this issue.

v3: update the WA number and explain the reason why
    this workaround is needed
v2: add WA number
v1: initial version

Signed-off-by: Angus Chen <angus.chen@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240426073638.45775-1-angus.chen@intel.com