[AArch64][SVE] Add one-use-check to EitherVSelectOrPassthruPatFrags

As pointed out in D149968 vselect predicate patterns could do with a one-use
check to prevent multiple operations being created. This updates the
EitherVSelectOrPassthruPatFrags pattern frags used in creating predicates
min/max.

Differential Revision: https://reviews.llvm.org/D151080