drivers: ipm: xlnx: fix AMD copyright

There is nothing like AMD-Xilinx Inc. That's why use full AMD name
instead.

Fixes: 09e2a4e9eb ("drivers: ipm: add zynqmp r5f support")
Co-developed-by: Mubin Sayyed <mubin.sayyed@amd.com>
Signed-off-by: Mubin Sayyed <mubin.sayyed@amd.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>

drivers/ipm/ipm_xlnx_ipi.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2023 AMD-Xilinx Inc.
+ * Copyright (c) 2023 Advanced Micro Devices, Inc.
  *
  * SPDX-License-Identifier: Apache-2.0
  */