[ARM] Don't generate deprecated T1 STM.
    
This prevents generating stm r1!, {r0, r1} on Thumb1, where value
stored for r1 is UNKONWN.

Patch by Zhaoshi Zheng.

Differential Revision: https://reviews.llvm.org/D27910



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296538 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed