tracing: move scripts/trace/power.pl to scripts/tracing/power.pl

Impact: Cleanup

We use scripts/tracing/ to contain tracing scripts.
Use one directory only instead of two.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <49D06B9C.3070209@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>