ACPI: Clean up incorrect inclusion of an ACPICA header

Since drivers/acpi/nvs.c includes <linux/acpi.h> and is only compiled
for CONFIG_ACPI set, it doesn't need to include <acpi/acpiosxf.h>
directly, which is formally incorrect.  Remove the <acpi/acpiosxf.h>
inclusion from that file.

Signed-off-by: Lv Zheng <lv.zheng@intel.com>
[rjw: Subject and changelog]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>