drivers/intel/fsp2_0: Support FSP 2.4 64-bits

FSP 2.4 brings FSP 64-bits support which requires some adjustments in
coreboot:

  FSP/UEFI uses the Microsoft x64 calling convention. Appropriate
  attribute has to be set to all functions calling or called by
  the FSP.

BUG=b:329034258
TEST=verified on Lunar Lake RVP board (lnlrvp)

Change-Id: If0397f5cc8d0f4f1872bd37a001fe42e0c37ec99
Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/80277
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Subrata Banik <subratabanik@google.com>
Reviewed-by: Krishna P Bhat D <krishna.p.bhat.d@intel.com>

src/include/efi/efi_datatype.h

@@ -81,6 +81,6 @@ typedef EFI_GUID efi_guid_t;
  */
 typedef
 void
-(EFIAPI *efi_ap_procedure)(void *buffer);
+(__efiapi *efi_ap_procedure)(void *buffer);
 
 #endif