[AArch64][SVE] Asm: Support for UZP and TRN instructions.

This patch adds support for:
  UZP1  Concatenate even elements from two vectors
  UZP2  Concatenate  odd elements from two vectors
  TRN1  Interleave  even elements from two vectors
  TRN2  Interleave   odd elements from two vectors

With variants for both data and predicate vectors, e.g.
  uzp1    z0.b, z1.b, z2.b
  trn2    p0.s, p1.s, p2.s

llvm-svn: 336531