Rm loadMemoryFromFile from Deprecated Roadmap, NFC (#2974)

Remove loadMemoryFromFile (and implicitly loadMemoryFromFileInline) from
the non-exhaustive list of deprecated things in the Roadmap.  This is
now planned to be supported by MFC [1].

[1]: https://github.com/llvm/circt/pull/4622



Signed-off-by: Schuyler Eldridge <schuyler.eldridge@sifive.com>