ASL: Use temporary variable when storing register into itself.

Otherwise it triggers a IASL warning with new IASL.

Change-Id: I090ee18df78ea779137ee6797c55b96ea27e6d27
Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
Reviewed-on: https://review.coreboot.org/13623
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>

src/mainboard/amd/dinar/dsdt.asl

@@ -802,7 +802,8 @@ DefinitionBlock (
                 }
 
                 /* Arbitrarily clear PciExpWakeStatus */
-                Store(PEWS, PEWS)
+                Store(PEWS, Local0)
+                Store(Local0, PEWS)
 
                 /* if(DeRefOf(Index(WKST,0))) {
                 *       Store(0, Index(WKST,1))

src/mainboard/amd/torpedo/dsdt.asl

@@ -774,7 +774,8 @@ DefinitionBlock (
 		}
 
 		/* Arbitrarily clear PciExpWakeStatus */
-		Store(PEWS, PEWS)
+		Store(PEWS, Local0)
+		Store(Local0, PEWS)
 
 		/* if(DeRefOf(Index(WKST,0))) {
 		*	Store(0, Index(WKST,1))