[ARM] Add some basic Min/Max costs

This adds basic MVE costs for SMIN/SMAX/UMIN/UMAX, as well as MINNUM and
MAXNUM representing fmin and fmax. It tightens up the costs, not using a
ICmp+Select cost.

Differential Revision: https://reviews.llvm.org/D96603

GitOrigin-RevId: 0a98efb049393a579a1e44a68bfa886475ea672c
3 files changed