ad9081: common: ad9081_fmca_ebz_bd: Fix ad_mem_interconnect clock

[bluncan]

PR Description

The ad_mem_hp1_interconnect for rx_dma was set to $sys_cpu_clock instead of $sys_dma_clock

PR Type

• [x] Bug fix (change that fixes an issue)
• [ ] 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 code style guidelines
• [x] I have performed a self-review of changes
• [x] I have compiled all hdl projects and libraries affected by this PR
• [ ] I have tested in hardware affected projects, at least on relevant boards
• [ ] I have commented my code, at least hard-to-understand parts
• [x] I have signed off all commits from this PR
• [ ] I have updated the documentation (wiki pages, ReadMe files, Copyright etc)
• [ ] I have not introduced new Warnings/Critical Warnings on compilation
• [ ] I have added new hdl testbenches or updated existing ones