intel/d945gclf: Fix IASL warning and remark

- Add an empty Operating Region for the empty _REG method
- Serialize _CRS Method
- Remove Kconfig default disabling IASL warnings as errors

dsdt.aml   1445:  Method (_CRS, 0)
Remark   2120 -             ^ Control Method should be made Serialized
(due to creation of named objects within)
dsdt.aml   1454:  Method (_REG, 2)
Warning  3079 -             ^ _REG has no corresponding Operation Region

Change-Id: I2b64609c929af62c2b699762206e5baf58fbdb8b
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: http://review.coreboot.org/12523
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/mainboard/intel/d945gclf/Kconfig

@@ -50,8 +50,4 @@ config MAX_CPUS
 	int
 	default 4
 
-# TODO: Remove this when platform ASL is fixed
-config IASL_WARNINGS_ARE_ERRORS
-	def_bool n
-
 endif # BOARD_INTEL_D945GCLF

src/mainboard/intel/d945gclf/acpi/ec.asl

@@ -18,7 +18,13 @@ Device(EC0)
 	Name (_HID, EISAID("PNP0C09"))
 	Name (_UID, 1)
 
-	Method (_CRS, 0)
+	// _REG method requires that an operation region be defined.
+	OperationRegion (ERAM, EmbeddedControl, 0x00, 0xff)
+	Field (ERAM, ByteAcc, Lock, Preserve)
+	{
+	}
+
+	Method (_CRS, 0, Serialized)
 	{
 		Name (ECMD, ResourceTemplate()
 		{