[MIPS] Fix modpost warning: Rename op_model_xxx to op_model_xxx_ops.

    
The modpost uses a whitelist for commonly used suffix on checking the
section mismatch.  Adding "_ops" suffix to op_modex_xxx get rid of
this modpost warning.
    
WARNING: arch/mips/oprofile/oprofile.o - Section mismatch: reference to .init.text: from .data after 'op_model_mipsxx' (at offset 0x528)

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>