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 <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/12518
Reviewed-by: Timothy Pearson <tpearson@raptorengineeringinc.com>
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

1 files changed, 0 insertions, 4 deletions

diff --git a/src/mainboard/lenovo/t400/Kconfig b/src/mainboard/lenovo/t400/Kconfig
index 8d258d98e945..467cd630b42c 100644
--- a/src/mainboard/lenovo/t400/Kconfig
+++ b/src/mainboard/lenovo/t400/Kconfig
@@ -51,8 +51,4 @@ config CBFS_SIZE
 	hex
 	default 0x200000
 
-# TODO: Remove this when platform ASL is fixed
-config IASL_WARNINGS_ARE_ERRORS
-	def_bool n
-
 endif # BOARD_LENOVO_T400