xilinx: Free memory when variable is saved in boot_targets_setup()

When boot_targets variable is saved there is no reason to keep string in
malloc area that's why free it. This change is already done in ZynqMP code.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/fa10fc22193a1a23258466056b3d02f7496fccfe.1744270729.git.michal.simek@amd.com

board/amd/versal2/board.c

@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2021 - 2022, Xilinx, Inc.
- * Copyright (C) 2022 - 2024, Advanced Micro Devices, Inc.
+ * Copyright (C) 2022 - 2025, Advanced Micro Devices, Inc.
  *
  * Michal Simek <michal.simek@amd.com>
  */
@@ -307,6 +307,7 @@ static int boot_targets_setup(void)
 				env_targets ? env_targets : "");
 
 		env_set("boot_targets", new_targets);
+		free(new_targets);
 	}
 
 	return 0;

board/xilinx/versal/board.c

@@ -283,6 +283,7 @@ static int boot_targets_setup(void)
 				env_targets ? env_targets : "");
 
 		env_set("boot_targets", new_targets);
+		free(new_targets);
 	}
 
 	return 0;