ci(n1sdp): refactor fip fragment for specificity

The ``n1sdp-fip`` fragment builds the fip image with UEFI. Replace the
fragment to target this specific use case as we also want to generate
fip images with other NS workloads i.e. TFTF. Move parts of the code for
creating a fip image with xCP firmware to a generic location so it may
be used by other fragments.

Signed-off-by: Harrison Mutai <harrison.mutai@arm.com>
Change-Id: I37433e32f1bc235e4c524ceed5730b0bc4c63ddd
diff --git a/run_config/n1sdp-firmware b/run_config/n1sdp-firmware
index 02bcf3a..e7c1a40 100644
--- a/run_config/n1sdp-firmware
+++ b/run_config/n1sdp-firmware
@@ -1,10 +1,14 @@
 #!/usr/bin/env bash
 #
-# Copyright (c) 2021 Arm Limited. All rights reserved.
+# Copyright (c) 2021-2023 Arm Limited. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
 
 fetch_tf_resource() {
-        n1sdp_firmware_bin_url="$n1sdp_prebuilts/n1sdp-board-firmware.zip" get_n1sdp_firmware
+        fetch_prebuilt_fw_images
+}
+
+post_fetch_tf_resource() {
+        gen_recovery_image
 }