ACPICA: Add support to allow host OS to redefine individual OSL prototypes.

This change enables the host OS to redefine OSL prototypes found in the
acpiosxf.h file. This allows the host OS to implement OSL interfaces with
a macro or inlined function. Further, it allows the host OS to add any
additional required modifiers such as __iomem, __init, __exit, etc.,
as necessary on a per-interface basis. Enables maximum flexibility
for the OSL interfaces. Lv Zheng.

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