MIPS: Netlogic: add r4k_wait as the cpu_wait

Use r4k_wait as the CPU wait function for XLR/XLS processors.

Signed-off-by: Jayachandran C <jayachandranc@netlogicmicro.com>
To: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2728/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>