[AArch64] Optimize compare and branch sequence when the compare's constant operand is power of 2

Summary:
Peephole optimization that generates a single TBZ/TBNZ instruction
for test and branch sequences like in the example below. This handles
the cases that miss folding of AND into TBZ/TBNZ during ISelLowering of BR_CC

Examples:
   and  w8, w8, #0x400
   cbnz w8, L1
 to
   tbnz w8, #10, L1

Reviewers: MatzeB, jmolloy, mcrosier, t.p.northover

Subscribers: aemerson, rengolin, mcrosier, llvm-commits

Differential Revision: http://reviews.llvm.org/D17942

llvm-svn: 263136