MIPS: Use hardware watchpoints on all R1 and R2 CPUs.

The previous definition inadvertently omits Octeon which currently is
treated as an architecture variant separate from MIPS32 and MIPS64.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>