mn10300: split ret_from_fork, simplify kernel_thread()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/mn10300/kernel/entry.S b/arch/mn10300/kernel/entry.S
index 8e11f9f..000f144 100644
--- a/arch/mn10300/kernel/entry.S
+++ b/arch/mn10300/kernel/entry.S
@@ -55,6 +55,13 @@
 	mov	d0,(REG_D0,fp)
 	jmp	syscall_exit
 
+ENTRY(ret_from_kernel_thread)
+	call	schedule_tail[],0
+	mov	(REG_D0,fp),d0
+	mov	(REG_A0,fp),a0
+	calls	(a0)
+	jmp	sys_exit
+
 ###############################################################################
 #
 # system call handler