Extend disabling SAMPLER_STATE prefetch workaround to gen12.

v2: Limit the WA to TGL A0 and update the WA no(Chris)

BSpec: 52890
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20191113231953.24853-1-radhakrishna.sripada@intel.com