SRAM API: Add multiple-clocked port API (backport #3383) (#3405)

* SRAM API: Add multiple-clocked port API (#3383)

This PR adds new APIs for the SRAM module to instantiate a number of ports connected to individual clocks. This allows the creation of memories driven by multiple clocks, for use cases like clock domain crossover.

(cherry picked from commit d79ae71e

)

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Co-authored-by: Jared Barocsi <82000041+jared-barocsi@users.noreply.github.com>
Co-authored-by: Jared Barocsi <jared.barocsi@sifive.com>