MIPS: Fix cpu_has_mips_r2_exec_hazard.

MIPS: Fix cpu_has_mips_r2_exec_hazard.

commit 9cdf30bd3bac697fc533988f44a117434a858f69 upstream.

Returns a non-zero value if the current processor implementation requires
an IHB instruction to deal with an instruction hazard as per MIPS R2
architecture specification, zero otherwise.

For a discussion, see http://patchwork.linux-mips.org/patch/9539/.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
[bwh: Backported to 3.2: trim the CPU type list]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>