[llvm] [RISCV][TTI] Enable masked interleave access (PR #151665)

[Mel Chen via llvm-commits]

Mel-Chen wrote:

> LGTM, I tested it out locally and can confirm its generating masked vlseg/vsseg as expected from the loop vectorizer, both for internal predication and with EVL tail folding.
> 
> I think the last two restrictions in the PR description just need updated now that they're removed.

Updated the title and description. Rebased and waiting for the test result.

https://github.com/llvm/llvm-project/pull/151665