feat(cpu): add Cortex X2 run config

This patch adds a run config for Cortex X2 along with other supporting
changes.

Signed-off-by: John Powell <john.powell@arm.com>
Change-Id: I5b0d0efbe899a50334d318ed447a5674031eff04
diff --git a/run_config/fvp-cortexx2 b/run_config/fvp-cortexx2
new file mode 100644
index 0000000..5a4c504
--- /dev/null
+++ b/run_config/fvp-cortexx2
@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+
+post_fetch_tf_resource() {
+        local model="cortex-x2"
+
+	model="$model" \
+	cache_state_modelled="0" \
+	gen_model_params
+	uart="0" set_expect_variable "num_cpus" "4"
+	model="$model" gen_fvp_yaml
+}