[AArch64] Refactor the scheduling predicates
[AArch64] Refactor the scheduling predicates

Refactor the scheduling predicates based on `MCInstPredicate`.  Augment the
number of helper predicates used by processor specific predicates.

Differential revision: https://reviews.llvm.org/D55375

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@348768 91177308-0d34-0410-b5e6-96231b3b80d8

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