[ARM] noMMU: block sys_fork in nommu mode

The sys_fork is not supported in nommu mode. The other syscalls
that is not supported in nommu mode are to be defined as cond_signal
in kernel/sys_ni.c.

Signed-off-by: Hyok S. Choi <hyok.choi@samsung.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/kernel/sys_arm.c b/arch/arm/kernel/sys_arm.c
index a491de2..8170af4 100644
--- a/arch/arm/kernel/sys_arm.c
+++ b/arch/arm/kernel/sys_arm.c
@@ -234,7 +234,12 @@
  */
 asmlinkage int sys_fork(struct pt_regs *regs)
 {
+#ifdef CONFIG_MMU
 	return do_fork(SIGCHLD, regs->ARM_sp, regs, 0, NULL, NULL);
+#else
+	/* can not support in nommu mode */
+	return(-EINVAL);
+#endif
 }
 
 /* Clone a task - this clones the calling program thread.