[MIPS] Enable support for the userlocal hardware register

Which will cut down the cost of RDHWR $29 which is used to obtain the
TLS pointer and so far being emulated in software down to a single cycle
operation.

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

include/asm-mips/system.h

@@ -67,6 +67,8 @@ do {									\
 	(last) = resume(prev, next, task_thread_info(next));		\
 	if (cpu_has_dsp)						\
 		__restore_dsp(current);					\
+	if (cpu_has_userlocal)						\
+		write_c0_userlocal(task_thread_info(current)->tp_value);\
 } while(0)
 
 /*