OvmfPkg: replace SECURE_BOOT_FEATURE_ENABLED with PcdSecureBootSupported

Drop the '-D SECURE_BOOT_FEATURE_ENABLED' compile time option,
use a new FeaturePcd instead.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

OvmfPkg/PlatformPei/Platform.c

@@ -222,9 +222,10 @@ ReserveEmuVariableNvStore (
   VariableStore = (EFI_PHYSICAL_ADDRESS)(UINTN)PlatformReserveEmuVariableNvStore ();
   PcdStatus     = PcdSet64S (PcdEmuVariableNvStoreReserved, VariableStore);
 
- #ifdef SECURE_BOOT_FEATURE_ENABLED
-  PlatformInitEmuVariableNvStore ((VOID *)(UINTN)VariableStore);
- #endif
+  if (FeaturePcdGet (PcdSecureBootSupported)) {
+    // restore emulated VarStore from pristine ROM copy
+    PlatformInitEmuVariableNvStore ((VOID *)(UINTN)VariableStore);
+  }
 
   ASSERT_RETURN_ERROR (PcdStatus);
 }