This CPU definition is redundant. The Cortex-A9 is defined as supporting multiprocessing extensions. Remove its definition and update appropriate tests.
LLVM defines both a cortex-a9 CPU and a cortex-a9-mp CPU. The only difference between the two CPU definitions in ARM.td is that cortex-a9-mp contains the feature FeatureMP for multiprocessing extensions.
This is redundant since the Cortex-A9 is defined as having multiprocessing extensions in the TRMs.
The following thread from last year has a discussion about the possibility of removing this CPU,
http://lists.cs.uiuc.edu/pipermail/cfe-dev/2013-November/033201.html
It appears as though the pseudo-architectures were removed, but the cortex-a9-mp CPU was not. Clang currently has no tests that depend on this CPU being in LLVM, so this patch will not break Clang tests, but I will prepare a separate patch for Clang to remove its references to this CPU name.