[MIPS] Fix register handling in syscalls when debugging.

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

arch/mips/kernel/scall64-64.S

@@ -93,13 +93,15 @@ syscall_trace_entry:
 	li	a1, 0
 	jal	do_syscall_trace
 
+	move	t0, s0
+	RESTORE_STATIC
 	ld	a0, PT_R4(sp)		# Restore argument registers
 	ld	a1, PT_R5(sp)
 	ld	a2, PT_R6(sp)
 	ld	a3, PT_R7(sp)
 	ld	a4, PT_R8(sp)
 	ld	a5, PT_R9(sp)
-	jalr	s0
+	jalr	t0
 
 	li	t0, -EMAXERRNO - 1	# error?
 	sltu	t0, t0, v0