gitlab: Add an rpi5 to the sjg lab

I have one of these 2GB boards with Ubuntu 24.10 loaded. Add an entry
for it so that it can be used for testing.

Series-to: u-boot
Series-cc: trini
Signed-off-by: Simon Glass <sjg@chromium.org>

.gitlab-ci.yml

@@ -731,3 +731,8 @@ rock5b:
   variables:
     ROLE: rock5b
   <<: *lab_dfn
+
+rpi5:
+  variables:
+    ROLE: rpi5
+  <<: *lab_dfn

boot/pxe_utils.c

@@ -1729,7 +1729,8 @@ struct pxe_menu *pxe_prepare(struct pxe_context *ctx, ulong pxefile_addr_r,
 		return NULL;
 	}
 
-	cfg->prompt = prompt;
+	if (prompt)
+		cfg->prompt = prompt;
 
 	return cfg;
 }