ACPI: delete acpi_os_free(), use kfree() directly

Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index e439eb7..8e9c26a 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -768,7 +768,7 @@
 		status = -EFAULT;
 
       end:
-	acpi_os_free(buffer.pointer);
+	kfree(buffer.pointer);
 
 	return status;
 }