[5/11][Clang][RISCV] Expand all variants for unit stride fault-first segment load

This is the 5th patch of the patch-set. For the cover letter, please
checkout D152069.

Depends on D152072.

This patch expands all variants of unit stride fault-first segment
load, including the policy variants. This patch also fixes the
trailing suffix in the intrinsics' function name that representing
the return type, adding `x{NF}`.

For the same reason mentioned in [3/11], only full test case for
vlseg2e32ff is added.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D152073