ftrace: Do not copy old hash when resetting

Do not waste time copying the old hash if the hash is going to be
reset. Just allocate a new hash and free the old one, as that is
the same result as copying te old one and then resetting it.

Link: http://lkml.kernel.org/p/1405384820-48837-1-git-send-email-wangnan0@huawei.com



Signed-off-by: Wang Nan <wangnan0@huawei.com>
[ SDR: Removed unused ftrace_filter_reset() function ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>