plat(fvp): use generic image fetching functions

Some generic functions have been provided for fetching prebuilt images -
use these for FVP runs.

Signed-off-by: Harrison Mutai <harrison.mutai@arm.com>
Change-Id: I785890c9b0370279230dfd6f71a54bcdc0ebc9c3
diff --git a/run_config/fvp-aemv8a.rst31 b/run_config/fvp-aemv8a.rst31
index dcf81d5..1d71848 100644
--- a/run_config/fvp-aemv8a.rst31
+++ b/run_config/fvp-aemv8a.rst31
@@ -1,12 +1,12 @@
 #!/usr/bin/env bash
 #
-# Copyright (c) 2019-2022, Arm Limited. All rights reserved.
+# Copyright (c) 2019-2023, Arm Limited. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
 
 post_tf_build() {
-	get_uboot_bin
+	url="$uboot_url" filename="uboot.bin" fetch_and_archive
 }
 
 generate_lava_job() {