[AArch64][SVE] Asm: Support for bitwise operations on predicate vectors.

This patch adds support for instructions performing bitwise operations
on predicate vectors, including AND, BIC, EOR, NAND, NOR, ORN, ORR, and
their status flag setting variants ANDS, BICS, EORS, NANDS, ORNS, ORRS.

This patch also adds several aliases:

  orr  p0.b, p1/z, p1.b, p1.b  => mov  p0.b, p1.b
  orrs p0.b, p1/z, p1.b, p1.b  => movs p0.b, p1.b

  and  p0.b, p1/z, p2.b, p2.b  => mov  p0.b, p1/z, p2.b
  ands p0.b, p1/z, p2.b, p2.b  => movs p0.b, p1/z, p2.b

  eor  p0.b, p1/z, p2.b, p1.b  => not  p0.b, p1/z, p2.b
  eors p0.b, p1/z, p2.b, p1.b  => nots p0.b, p1/z, p2.b

llvm-svn: 334906