[7/11][Clang][RISCV] Expand all variants for strided segment store

This is the 7th patch of the patch-set. For the cover letter, please
checkout D152069.

Depends on D152074.

This patch expands all variants for strided segment store. The store
intrinsics does not have any 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
vssseg2e32 is added for now.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D152075