asus/m2v: Make _CRS methods serialized

Address the iasl 20160108-64 (Ubuntu 16.04) warnings below.

```
Intel ACPI Component Architecture
ASL+ Optimizing Compiler version 20160108-64
Copyright (c) 2000 - 2016 Intel Corporation

dsdt.aml    245:      Method (_CRS, 0, NotSerialized)
Remark   2120 -                 ^ Control Method should be made Serialized (due to creation of named objects within)

dsdt.aml    262:      Method (_CRS, 0, NotSerialized)
Remark   2120 -                 ^ Control Method should be made Serialized (due to creation of named objects within)

dsdt.aml    277:      Method (_CRS, 0, NotSerialized)
Remark   2120 -                 ^ Control Method should be made Serialized (due to creation of named objects within)

dsdt.aml    295:    Method(_CRS, 0) {
Remark   2120 -              ^ Control Method should be made Serialized (due to creation of named objects within)
```

Change-Id: Id5b0f33fba8ea25e4a6aa4f01c69a69aaf5aef23
Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
Reviewed-on: https://review.coreboot.org/18323
Tested-by: build bot (Jenkins)
Reviewed-by: Tobias Diedrich <ranma+coreboot@tdiedrich.de>
Reviewed-by: Martin Roth <martinroth@google.com>
1 file changed