Get utility script name from TF configuration

The problem was found with CI build scripts when building rdn1edgex2
platform. Both rdn1edge and rdn1edgex2 have PLAT=rdn1edge in their TF
configs (which is correct, as there is no rdn1edgex2 build option
for TF-A).The problem is that PLAT sets 'plat' variable which is used
to call ${plat}_utils.sh and rdn1edge_utils.sh is called instead of
rdn1edgex2_utils.sh.

To resolve this issue introduced a new config parameter “SCRIPT_NAME”
inside the TF configuration which is used to source the utility script
for e.g. rdn1edge_utils.sh.

Change-Id: I5c50f71acc77f0bb2d24393e784360adb36adf95
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
diff --git a/script/build_package.sh b/script/build_package.sh
index 2c61f05..cd5caf2 100755
--- a/script/build_package.sh
+++ b/script/build_package.sh
@@ -1194,9 +1194,17 @@
 		(
 		echo "##########"
 
-		# Source platform-specific utilities
-		plat="$(get_tftf_opt PLAT)"
-		plat_utils="$ci_root/${plat}_utils.sh"
+		plat_utils="$(get_tf_opt PLAT_UTILS)"
+		if [ -z ${plat_utils} ]; then
+			# Source platform-specific utilities.
+			plat="$(get_tftf_opt PLAT)"
+			plat_utils="$ci_root/${plat}_utils.sh"
+		else
+			# Source platform-specific utilities by
+			# using plat_utils name.
+			plat_utils="$ci_root/${plat_utils}.sh"
+		fi
+
 		if [ -f "$plat_utils" ]; then
 			source "$plat_utils"
 		fi
@@ -1226,9 +1234,17 @@
 		(
 		echo "##########"
 
-		# Source platform-specific utilities
-		plat="$(get_tf_opt PLAT)"
-		plat_utils="$ci_root/${plat}_utils.sh"
+		plat_utils="$(get_tf_opt PLAT_UTILS)"
+		if [ -z ${plat_utils} ]; then
+			# Source platform-specific utilities.
+			plat="$(get_tf_opt PLAT)"
+			plat_utils="$ci_root/${plat}_utils.sh"
+		else
+			# Source platform-specific utilities by
+			# using plat_utils name.
+			plat_utils="$ci_root/${plat_utils}.sh"
+		fi
+
 		if [ -f "$plat_utils" ]; then
 			source "$plat_utils"
 		fi