MIPS: perf: Remove unnecessary #ifdef

MIPS: perf: Remove unnecessary #ifdef

The #ifdef for CONFIG_HW_PERF_EVENTS is not needed because the
Makefile will only compile the module if this config option is set.
This means that the code under #else would never be compiled. This
may have been done to leave the original broken code around for
reference, but the FIXME comment above the code already shows the
broken code.

Signed-off-by: Al Cooper <alcooperx@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/4107/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>