[LLDB][MIPS] XFAIL TestCrashDuringStep.py for MIPS

    SUMMARY:
    Marked TestCrashDuringStep.py as XFAIL for MIPS. The test generates IO error due to breakpoint at invalid address.
    
    Reviewers: clayborg, labath
    Subscribers: nitesh.jain, mohit.bhakkad, sagar, bhushan and lldb-commits
    Differential Revision: http://reviews.llvm.org/D15182

llvm-svn: 254710