[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