olpc_xo15_sci: convert acpi_evaluate_object() to acpi_execute_simple_method()

acpi_execute_simple_method() is a new ACPI API introduced to invoke
an ACPI control method that has single integer parameter and no return value.

Convert acpi_evaluate_object() to acpi_execute_simple_method()
in arch/x86/platform/olpc/olpc-xo15-sci.c

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
CC: Daniel Drake <dsd@laptop.org>
CC: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>