Blackfin: delete fork func

We don't implement fork() since we are no-mmu, so redirect it to the
existing ENOSYS stub rather than adding a custom EINVAL one.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Bob Liu <lliubbo@gmail.com>
diff --git a/arch/blackfin/mach-common/entry.S b/arch/blackfin/mach-common/entry.S
index 84b5e3d..80aa253 100644
--- a/arch/blackfin/mach-common/entry.S
+++ b/arch/blackfin/mach-common/entry.S
@@ -1377,7 +1377,7 @@
 ENTRY(_sys_call_table)
 	.long _sys_restart_syscall	/* 0 */
 	.long _sys_exit
-	.long _sys_fork
+	.long _sys_ni_syscall	/* fork */
 	.long _sys_read
 	.long _sys_write
 	.long _sys_open		/* 5 */