alpha: ret_from_fork can go straight to ret_to_user

We only hit ret_from_fork when the child is meant to return to
userland (since 2012 or so).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/alpha/kernel/entry.S

@@ -766,7 +766,7 @@ alpha_switch_to:
 	.align	4
 	.ent	ret_from_fork
 ret_from_fork:
-	lda	$26, ret_from_sys_call
+	lda	$26, ret_to_user
 	mov	$17, $16
 	jmp	$31, schedule_tail
 .end ret_from_fork