[AArch64][SVE] Add patterns for some arith SVE instructions.

Summary: Add patterns for the following instructions:
- smax, smin, umax, umin

Reviewers: sdesmalen, huntergr, rengolin, efriedma, c-rhodes, mgudim, kmclaughlin

Subscribers: amehsan

Differential Revision: https://reviews.llvm.org/D71779