ARM: Add instruction aliases for the Thumb2 PLD/PLDW (literal) alternate form.

See A8.8.127 in ARM DDI 0406C.b.

Related to <rdar://problem/14403733>.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186682 91177308-0d34-0410-b5e6-96231b3b80d8