[llvm] [RISCV][MC] Support Assembling 48- and 64-bit Instructions (PR #110022)

[Jessica Clarke via llvm-commits]

jrtc27 wrote:

https://github.com/riscv/riscv-isa-manual/blob/7023c601443adf21850772e02e3d920bc68b2237/src/intro.adoc?plain=1#L496 seems to still be there

https://github.com/llvm/llvm-project/pull/110022