[9/11][Clang][RISCV] Expand all variants for indexed strided segment store

[9/11][Clang][RISCV] Expand all variants for indexed strided segment store

This is the 9th patch of the patch-set. For the cover letter, please
checkout D152069.

Depends on D152076.

This patch expands all variants of indexed strided segment store.
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
vsuxseg2ei32, vsoxseg2ei32 is added for now.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D152077