[AArch64][SME] Add SVE2 instructions added in SME

This patch adds support for the following instructions:

    SCLAMP, UCLAMP, REV, DUP (predicate)

The reference can be found here:
https://developer.arm.com/documentation/ddi0602/2021-06

Reviewed By: kmclaughlin

Differential Revision: https://reviews.llvm.org/D105577