MIPS: pm-cps: Use MIPS standard completion barrier

SYNC type 0 is defined in the MIPS architecture as a completion barrier
where all loads/stores in the pipeline before the sync instruction must
complete before any loads/stores subsequent to the sync instruction.

In places where we require loads / stores be globally completed, use the
standard completion 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: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14224/


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