lib: Update fmap cache error for psp_verstage

The assumption was that the fmap cache would be initialized in
bootblock, otherwise an error is shown.  This error is showing
up in psp_verstage when the fmap cache is initialized there, so
create a new ENV value for ENV_INITIAL_STAGE.

BUG=None
TEST=Boot, see that error message is gone from psp_verstage

Signed-off-by: Martin Roth <martinroth@chromium.org>
Change-Id: I142f2092ade7b4327780d423d121728bfbdab247
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43488
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/lib/fmap.c b/src/lib/fmap.c
index 671a962..e1e6a57 100644
--- a/src/lib/fmap.c
+++ b/src/lib/fmap.c
@@ -56,9 +56,8 @@
 	}
 
 	struct fmap *fmap = (struct fmap *)_fmap_cache;
-	if (!ENV_BOOTBLOCK) {
-		/* NOTE: This assumes that for all platforms running this code,
-		   the bootblock is the first stage and the bootblock will make
+	if (!(ENV_INITIAL_STAGE)) {
+		/* NOTE: This assumes that the first stage will make
 		   at least one FMAP access (usually from finding CBFS). */
 		if (!check_signature(fmap))
 			goto register_cache;