target/mips: Guard check_insn with INSN_R5900 check

Explicitely mark handling of PREF instruction for R5900 as
treating the same as NOP.

Reviewed-by: Aleksandar Markovic <amarkovic@wavecomp.com>
Signed-off-by: Fredrik Noring <noring@nocrew.org>
Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
1 file changed