The pdtlb and pitlb instructions are strongly ordered. The asms invoking
these instructions should be compiler memory barriers to ensure the
compiler doesn't reorder memory operations around these instructions.

Signed-off-by: John David Anglin <dave.anglin@bell.net>
CC: stable@vger.kernel.org # v4.20+
Fixes: 3847dab7 ("parisc: Add alternative coding infrastructure")
Signed-off-by: Helge Deller <deller@gmx.de>