MIPS: pm-cps: Use MIPS standard lightweight ordering barrier

Since R2 of the MIPS architecture, SYNC(0x10) has been an optional but
architecturally defined ordering barrier. If a CPU does not implement it,
the arch specifies that it must fall back to SYNC(0).

In places where we require that the instruction stream not be reordered,
but do not require that loads / stores are gloablly completed, use the
defined standard sync stype.

Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Reviewed-by: Paul Burton <paul.burton@imgtec.com>
Cc: Adam Buchbinder <adam.buchbinder@gmail.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14221/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>