cpufreq: arm_big_little_dt: Free opp table from referenced CPU

cpufreq: arm_big_little_dt: Free opp table from referenced CPU

When opp table is defined only one for each CLUSTER, opp table might
not be freed even all CPUs in CLUSTER hoplugged off unless last CPU
was referenced one. And un-freed opp table occurs annoying warning
messages when CPU hotplugged on again.

<Warning Log>
[ 2931.471956] cpu cpu4: _opp_add_dynamic: duplicate OPPs detected ~

So it fixes it to work corretly with modifying freeing procedure.
If last CPU is not the referenced one which holds opp table for CLUSTER,
it tries to find opp table from other sibling CPUs. Otherwise, it just
free itself's.

Signed-off-by: Jonghwa Lee <jonghwa3.lee@samsung.com>