generic-ipi: Kill unnecessary variable - csd_flags

After commit 8969a5ed
("generic-ipi: remove kmalloc()"), wait = 0 can be guaranteed,
and all callsites of generic_exec_single() do an unconditional
csd_lock() now.

So csd_flags is unnecessary now. Remove it.

Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Link: http://lkml.kernel.org/r/51F72DA1.7010401@huawei.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>