[RISCV][IA] Support masked.store of deinterleaveN intrinsic (#149893)
This is the masked.store side to the masked.load support added in
881b3fd.
With this change, we support masked.load and masked.store via the
intrinsic lowering path used primarily with scalable vectors. An
upcoming change will extend the fixed vector (i.a. shuffle vector) paths
in the same manner.