mips: switch to generic sys_fork() and sys_clone()

we still need the wrappers to store callee-saved registers in
pt_regs, but once that done we can jump to kernel/fork.c variants.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/mips/kernel/scall64-n32.S

@@ -159,8 +159,8 @@ EXPORT(sysn32_call_table)
 	PTR	sys_socketpair
 	PTR	compat_sys_setsockopt
 	PTR	sys_getsockopt
-	PTR	sys_clone			/* 6055 */
-	PTR	sys_fork
+	PTR	__sys_clone			/* 6055 */
+	PTR	__sys_fork
 	PTR	compat_sys_execve
 	PTR	sys_exit
 	PTR	compat_sys_wait4