MIPS: ftrace: Enable support for syscall tracepoints.

All the necessary support code is already there so all that's left is
to enable the feature in kconfig.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/Kconfig

@@ -21,6 +21,7 @@ config MIPS
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_KPROBES
 	select HAVE_KRETPROBES
+	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_DEBUG_KMEMLEAK
 	select HAVE_SYSCALL_TRACEPOINTS
 	select ARCH_HAS_ELF_RANDOMIZE