import-creds: when we hit ENOENT on SMBIOS 11 do not even debug log

We'll *always* hit ENEOENT when iterating through SMBIOS type systemd#11
fields, on the last one. it's very confusing to debug log about that,
let's just not do it.

(cherry picked from commit 5202ee42d5da0ae3a6655d2bc959a19d8c347e9d)
(cherry picked from commit 995c702a347d16cfad4605f3982d5278616ea1f8)
(cherry picked from commit f084959)

src/core/import-creds.c

@@ -595,9 +595,11 @@ static int import_credentials_smbios(ImportCredentialContext *c) {
                         return log_oom();
 
                 r = read_virtual_file(p, sizeof(dmi_field_header) + CREDENTIALS_TOTAL_SIZE_MAX, (char**) &data, &size);
+                if (r == -ENOENT) /* Once we reach ENOENT there are no more DMI Type 11 fields around. */
+                        break;
                 if (r < 0) {
                         /* Once we reach ENOENT there are no more DMI Type 11 fields around. */
-                        log_full_errno(r == -ENOENT ? LOG_DEBUG : LOG_WARNING, r, "Failed to open '%s', ignoring: %m", p);
+                        log_warning_errno(r, "Failed to open '%s', ignoring: %m", p);
                         break;
                 }