projects: iio_demo: update xilinx hw file

[amiclaus]

Pull Request Description

With https://github.com/analogdevicesinc/hdl/pull/1208 the ad40xx hdl project was renamed to pulsar adc, therefore the hdl artifacts have a different name now, althought this should not have an impact on the functionality of the project for xilinx platform.

PR Type

• [ ] Bug fix (change that fixes an issue)
• [x] New feature (change that adds new functionality)
• [ ] Breaking change (has dependencies in other repos or will cause CI to fail)

PR Checklist

• [x] I have followed the Coding style guidelines
• [x] I have performed a self-review of the changes
• [ ] I have commented my code, at least hard-to-understand parts
• [ ] I have build all projects affected by the changes in this PR
• [ ] I have tested in hardware affected projects, at the relevant boards
• [x] I have signed off all commits from this PR
• [ ] I have updated the documentation (wiki pages, ReadMe etc), if applies