refactor: re-use run config fragments for TC platform variants

Several platforms have multiple variants, yet, they share most of the
software binaries and hence can utilize common run fragments. This
removes the need to maintain run fragments on per-variant basis.

We do this by introducing an environment variable `plat_variant` that
is populated from build parameter `TARGET_PLATFORM`

Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
Change-Id: I4218942b33dd32440a1ce9f7e78627bbe6710a69
diff --git a/script/build_package.sh b/script/build_package.sh
index 099a82a..10d1df4 100755
--- a/script/build_package.sh
+++ b/script/build_package.sh
@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 #
-# Copyright (c) 2019-2020 Arm Limited. All rights reserved.
+# Copyright (c) 2019-2021 Arm Limited. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
@@ -1371,6 +1371,8 @@
 		echo "##########"
 
 		plat_utils="$(get_tf_opt PLAT_UTILS)"
+		export plat_variant="$(get_tf_opt TARGET_PLATFORM)"
+
 		if [ -z ${plat_utils} ]; then
 			# Source platform-specific utilities.
 			plat="$(get_tf_opt PLAT)"