examples/vm_power: add core list parameter

Add in the '-l' command line parameter (also --core-list)
So the user can now pass --corelist=4,6,8-10 and it will
expand out to 4,6,8,9,10 using the parse function provided
in parse.c (parse_set).

This list of cores is then used to enable out-of-band monitoring
to scale up and down these cores based on the ratio of branch
hits versus branch misses. The ratio will be low when a poll
loop is spinning with no packets being received, so the frequency
will be scaled down.

Also , as part of this change, we introduce a core_info struct
which keeps information on each core in the system, and whether
we're doing out of band monitoring on them.

Signed-off-by: David Hunt <david.hunt@intel.com>
Acked-by: Radu Nicolau <radu.nicolau@intel.com>