[ARM] Size reduce teq to eors

Add t2TEQrr to the map of instructions with can be reduced down into
a T1 instruction. This is a special case because TEQ just sets the
CPSR and doesn't write to a GPR, which is not the case for EOR. So,
we need to ensure that the EOR can write to the first operand.

Differential Revision: https://reviews.llvm.org/D56255

llvm-svn: 350801