ftrace: Factor out __ftrace_hash_move()

The __ftrace_hash_move() is to allocates properly-sized hash and move
entries in the src ftrace_hash.  It will be used to set function graph
filters which has nothing to do with the dyn_ftrace records.

Link: http://lkml.kernel.org/r/20170120024447.26097-1-namhyung@kernel.org



Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>