docs(chip_porting): fix broken xTS test-case link in porting guide

[tanghao-xiaomi]

What

Fix a broken link in zh-cn/chip_porting/porting_guide.md. The "xTS test case collection" link was an unfilled placeholder:

/document?id=XXX&version=trunk&language=cn

Issues:

• id=XXX was never filled in;
• version=trunk is wrong for the contest branch;
• it used an absolute doc-site URL, inconsistent with the relative links used everywhere else in this file.

Fix

Point it to the real document via a relative path, consistent with the rest of the file:

../test_dev_guide/openvela_xts_test_cases.md

The target doc zh-cn/test_dev_guide/openvela_xts_test_cases.md already exists, and the English counterpart (en/chip_porting/porting_guide.md) already links to it correctly — only the Chinese version still had the placeholder.

Changes

• 1 file changed, 1 insertion(+), 1 deletion(-)