UefiPayloadPkg: Fix calling convention

When register a root SMI handler, it is expected to use windows calling
convention for the SMI handler. This patch adds missing EFIAPI for the
SMI handler SmmSwDispatcher to avoid potential issue from Linux build.

Signed-off-by: Guo Dong <guo.dong@intel.com>

UefiPayloadPkg/PchSmiDispatchSmm/PchSmiDispatchSmm.c

@@ -87,6 +87,7 @@ FindContextByDispatchHandle (
 
 **/
 EFI_STATUS
+EFIAPI
 SmmSwDispatcher (
   IN     EFI_HANDLE  DispatchHandle,
   IN     CONST VOID  *RegisterContext,