A peripheral's reset also resets the ones it occupies, so a lock has to cover
both. Gate the ECDSA MPI lock on SOC_ECDSA_USES_MPI rather than the runtime
ecdsa_ll_is_mpi_required() and set that capability on C5, lock the Key Manager
path in esp_key_mgr.c, clean HMAC after its reset, and enable DS before the
primitives its reset covers.
The Key Manager hardware peripheral in its current form needs further
design changes before it can be offered as a production feature.
Until a revised peripheral design is available, withdraw ESP-IDF
support for it on all Key Manager capable targets.