ACPICA: Cleanup coding style to reduce differences between Linux and ACPICA.

This is a cosmetic patch only. Comparison of the resulting binary showed
only line number differences.

This patch does not affect the generation of the Linux binary.
This patch decreases 314 lines of 20121018 divergence.diff.

ACPICA core uses ()'s on return statements. This is a known and committed
differences from Linux standard coding style.

This patch cleans up the Linux side ACPICA code to use this codying style
in order to reduce the source code differences between Linux and ACPICA.

Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>