rcu: just rename call_rcu_bh instead of making it a macro

Seems that I found a box that has a config that passes call_rcu_bh as a
function pointer (see net/sctp/sm_make_chunk.c), so declaring the
call_rcu_bh has a macro function isn't good enough.

This patch makes it just another name of call_rcu for rcupreempt.

Signed-off-by: Steven Rostedt <[e-mail]>
Reviewed-by: "Paul E. McKenney" <[e-mail]>
Signed-off-by: Ingo Molnar <[e-mail]>

include/linux/rcupreempt.h

···
 	rdssp->sched_qs++;
 }
 #define rcu_bh_qsctr_inc(cpu)
-#define call_rcu_bh(head, rcu) call_rcu(head, rcu)
+
+/*
+ * Someone might want to pass call_rcu_bh as a function pointer.
+ * So this needs to just be a rename and not a macro function.
+ *  (no parentheses)
+ */
+#define call_rcu_bh	 	call_rcu
 
 /**
  * call_rcu_sched - Queue RCU callback for invocation after sched grace period.