[TestGdbRemoteRegisterState] Do not flip ARM *psr register in the test

Summary:
Not all of that register is readable/writable in user mode. This means
that even if the inferior is stopped, parts of the register could be
changing. So, do not flip this register to check if its value can be
restored.

Reviewers: tberghammer, chaoren

Reviewed By: tberghammer

Subscribers: rengolin, aemerson, lldb-commits

Differential Revision: http://reviews.llvm.org/D10204

llvm-svn: 239104