According to HAS it is necessary to emit this instruction once per
context so MI_MEM_FENCE works properly.
Fixes: 86813c60a4 ("mi-builder: add read/write memory fencing support on Gfx20+")
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32680>