[PATCH v4] RISC-V: Gate opcode tables by enum rather than string

[Jim Wilson]

Now that we are post the binutils-2.33 branch and the GNU Cauldron
I've committed the v4 patch.  I took the ChangeLog entries from the v2
patch and updated them a bit, as a few functions/structs weren't
mentioned in the older ChangeLog entries.

Jim