[ARM] "cortex-r5f" and "cortex-m4f" are unknown names for clang.

The tests in test/CodeGen/arm-target-features.c are currently
passing but warning messages are suppressed. These tests are now
synchronized with the corresponding changes in Target Parser.

This patch will fix the regressions in clang caused by r247136

Differential Revision: http://reviews.llvm.org/D12722

llvm-svn: 247138