powerpc: Wire up sys_mlock2()

The selftest passes on 64-bit LE and 32-bit BE.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/include/asm/systbl.h b/arch/powerpc/include/asm/systbl.h
index c9e26cb..f2b0b1b 100644
--- a/arch/powerpc/include/asm/systbl.h
+++ b/arch/powerpc/include/asm/systbl.h
@@ -382,3 +382,4 @@
 SYSCALL(shmdt)
 SYSCALL(shmget)
 COMPAT_SYS(shmctl)
+SYSCALL(mlock2)