Support XuanTie E906 CPU.

[goodnorning]

PR checklist

• Add ThreadX porting codes for XuanTie E906.
• Add example for XuanTie E906 running on QEMU smartl.
• Validated on QEMU smartl platform.

[fdesbiens]

Hi @goodnorning.

Thank you very much for this contribution. Enabling support for the XuanTie family would be an important step forward for the project.

I will ask a senior member of the team to review the code.

The files you submitted refer to the Apache v2.0 license. Eclipse ThreadX, however, is licensed under the MIT license.

Would you be so kind as to replace the copyright headers and update the PR, please? For your convenience, I included a properly formatted sample header below.

/***************************************************************************
 * Copyright (C) 2017-2024 Alibaba Group Holding Limited
 * 
 * This program and the accompanying materials are made available under the
 * terms of the MIT License which is available at
 * https://opensource.org/licenses/MIT.
 * 
 * SPDX-License-Identifier: MIT
 **************************************************************************/

Thank you for your understanding.

[jserv]

T-Head XuanTie E906 is compatible with the RISC-V RV32IMA[F][D][C][P] ISA. Therefore, the XuanTie E906 port should reside under ports/risc-v32/gnu rather than ports/xuantie/e906/gnu to maintain directory consistency.