commit adfed2b0 upstream.

Avoids HDP cache flush issues when using vram which can
cause ring test failures on certain boards.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: Alexander Fyodorov <halcy@yandex.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>