ibase/mb899: Fix IASL warning and remark

- Add an empty Operating Region for the empty _REG method
- Move Named objects out of _CRS Method
- Remove Kconfig default disabling IASL warnings as errors

Fixes these items:
dsdt.aml 1449:  Method (_CRS, 0)
Remark   2120 -           ^ Control Method should be made Serialized
(due to creation of named objects within)
dsdt.aml 1458: Method (_REG, 2)
Warning  3079 -          ^ _REG has no corresponding Operation Region

Change-Id: I801a84468097687c91d6ee3f44cec06243355fac
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/12531
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/mainboard/ibase/mb899/Kconfig

@@ -49,8 +49,4 @@ config VGA_BIOS_FILE
 	string
 	default "amipci_01.20"
 
-# TODO: Remove this when platform ASL is fixed
-config IASL_WARNINGS_ARE_ERRORS
-	def_bool n
-
 endif # BOARD_IBASE_MB899

src/mainboard/ibase/mb899/acpi/ec.asl

@@ -18,14 +18,18 @@ Device(EC0)
 	Name (_HID, EISAID("PNP0C09"))
 	Name (_UID, 1)
 
-	Method (_CRS, 0)
-	{
+	// _REG method requires that an operation region is defined.
+	OperationRegion (ERAM, EmbeddedControl, 0x00, 0xff)
+	Field (ERAM, ByteAcc, Lock, Preserve) {}
+
 	Name (ECMD, ResourceTemplate()
 	{
 		IO (Decode16, 0x62, 0x62, 0, 1)
 		IO (Decode16, 0x66, 0x66, 0, 1)
 	})
 
+	Method (_CRS, 0, NotSerialized)
+	{
 		Return (ECMD)
 	}