Add a Thumb BRIND pattern. Change the ARM BRIND assembly to separate the

Add a Thumb BRIND pattern.  Change the ARM BRIND assembly to separate the
opcode and operand with a tab.  Check for these instructions in the usual
places.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85411 91177308-0d34-0410-b5e6-96231b3b80d8