[entropy_src] Enabling ENTROPY_DATA prevents CSRNG from getting entropy
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IP:entropy_src
Subsystem:Entropy
Type:FutureRelease
Type:Question
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Description
### Description
When ENTROPY_DATA register is enabled for software, CSRNG can no longer be instantiated with entropy directly from entropy source ([flag0=false](https://opentitan.org/book/hw/ip/csrng/doc/theory_of_operation.html#command-description)). While this is [documented behavior](https://opentitan.org/book/hw/ip/entropy_src/doc/theory_of_operation.html#routing-entropy-to-firmware), it is not desirable.
Current workaround - withdraw entropy in software and provide it with instantiate command to CSRNG (both for software and for EDN use), but it drops FIPS bit.
@moidx , @vogelpi
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