next: fix Rust TF-A build for QEMU

Correct the basic structure and files for Rust CI scripts:

 * Remove comments from tf_config files. This avoids the comment
   distorting the make command.
 * Run pre_tf_build with the correct tf_root path

Change-Id: I2163e4e7d9bf86fe18985978219d0a6672fe3be0
Signed-off-by: Tomás González <tomasagustin.gonzalezorlando@arm.com>
diff --git a/group/tf-next-build/qemu-next:nil b/group/tf-next-build/qemu-next:nil
index 77caa49..93b1998 100644
--- a/group/tf-next-build/qemu-next:nil
+++ b/group/tf-next-build/qemu-next:nil
@@ -5,6 +5,6 @@
 # SPDX-License-Identifier: BSD-3-Clause
 #
 pre_tf_build() {
-	make -C rust
-	make -C rust clippy
+	make -C "$tf_root/rust"
+	make -C "$tf_root/rust" clippy
 }
diff --git a/tf_config/fvp-next b/tf_config/fvp-next
index 19363ec..e69de29 100644
--- a/tf_config/fvp-next
+++ b/tf_config/fvp-next
@@ -1,5 +0,0 @@
-#
-# Copyright (c) 2024 Arm Limited. All rights reserved.
-#
-# SPDX-License-Identifier: BSD-3-Clause
-#
diff --git a/tf_config/qemu-next b/tf_config/qemu-next
index 19363ec..e69de29 100644
--- a/tf_config/qemu-next
+++ b/tf_config/qemu-next
@@ -1,5 +0,0 @@
-#
-# Copyright (c) 2024 Arm Limited. All rights reserved.
-#
-# SPDX-License-Identifier: BSD-3-Clause
-#