[MIPS] Always install the DSP exception handler.

Some non-DSP enabled cores 24K / 34K can generate a DSP exception where they
are actually expected to produce a reserved instruction exception.

Signed-off-by: Chris Dearman <chris@mips.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --cc arch/mips/kernel/traps.c
Simple merge