Update ad9208.c

[JIH82]

changed clock rates to support -625 variant these were 625e6 phy->ad9208.input_clk_min_hz = 240000000ULL; phy->ad9208.adc_clk_min_hz = 240000000ULL;

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PR Checklist

• [ ] I have conducted a self-review of my own code changes
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