Create Thumb2sI_cpsr and T2sI_cpsr. These new classes indicate that CPSR is the

optional modified register (instead of reg0). Along with r112461 it will make
sure that the optional define of CPSR is marked as "def" and will thus mark the
instructions using these classes (t2ANDS*) as setting the 's' flag.

llvm-svn: 112462