[RISCV] Refactor conversion of B extensions to IR intrinsics a little to reduce clang binary size.

These all pass 1 type to getIntrinsic. So rather than assigning
IntrinsicTypes for each builtin which invokes the SmallVector
constructor, just select the intrinsic ID with a switch and
share a single assignment of IntrinsicTypes.

GitOrigin-RevId: b4f2e8060075761dd0e9727ea01ca0142b4e767f
1 file changed