Patch merged into coreboot/master: lenovo t400: Fix IASL warning and remark

the following patch was just integrated into master:
commit 601ea3d40e39bb528f6418757ae3e8482920198f
Author: Martin Roth 
Date:   Mon Nov 23 12:37:22 2015 -0700

lenovo t400: Fix IASL warning and remark

If any path in a method returns a value, IASL expects that all paths
    within that method will return a value.

Presumably, the ATPX would not need a return value if Arg0 is anything
    other than 0, so just return a zero.

- Serialize ATPX method to make IASL happy.  This means that it can
    only be used by one thread at a time.

Fixes these issues:
    dsdt.aml   2581: Method (ATPX, 2, NotSerialized) {
    Remark   2120 -            ^ Control Method should be made Serialized
    (due to creation of named objects within)
    dsdt.aml 2581: Method (ATPX, 2, NotSerialized) {
    Warning  3115 -          ^ Not all control paths return a value (ATPX)

Change-Id: I14aeab0cebe4596e06a17cffc36cc01b953d7191
    Signed-off-by: Martin Roth 
    Reviewed-on: https://review.coreboot.org/12518
    Reviewed-by: Timothy Pearson 
    Tested-by: build bot (Jenkins)
    Reviewed-by: Stefan Reinauer

See https://review.coreboot.org/12518 for details.

-gerrit