[clang] [llvm] [RISCV] Make Zbc imply Zbkc. (PR #185543)

[Craig Topper via cfe-commits]

topperc wrote:

> Do we need to change the usage of `HasStdExtZbcOrZbkc` to `HasStdExtZbkc`

I think that would change the assembler diagnostic which is why I didn't do it.

https://github.com/llvm/llvm-project/pull/185543