util/smmstoretool: explain what happens when no store is found

We are going to expose ths tool to end users, and want to take
care that the presented information can be consumed by them.

The current code simply prints below warnings if we use release
binary available for end-user to download:

No firmware volume header present
No valid firmware volume was found

It will be concerning and not clear to end users, they might not
understant why it happens, what are the implications, and whether
it is something that they should worry about.

This commit tries to explain what actually happens here.

Change-Id: Iaa2678f5ae7c243811484c0567ced97ae0b3fc0a
Signed-off-by: Maciej Pijanowski <maciej.pijanowski@3mdeb.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/82692
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Sergii Dmytruk <sergii.dmytruk@3mdeb.com>

util/smmstoretool/storage.c

@@ -50,6 +50,12 @@ bool storage_open(const char store_file[], struct storage_t *storage, bool rw)
 			goto error;
 		}
 
+		fprintf(stderr,
+			"\nThe variable store has not been found in the ROM image\n"
+			"and is about to be initialized. This situation is normal\n"
+			"for a release image, as the variable store is usually\n"
+			"initialized on the first boot of the platform.\n\n");
+
 		if (!fv_init(storage->region)) {
 			fprintf(stderr,
 				"Failed to create variable store in \"%s\"\n",