sched: Update min/max capacity for the CPUFREQ_CREATE_POLICY notifier

Following the change "57e29051 sched: Skip resetting HMP stats when
max frequencies remain unchanged" the scheduler fails to update
min/max capacities appropriately when CPUs are hot added after being
hot removed. Fix this problem by handling the CPUFREQ_CREATE_POLICY
notification and explicitly updating min/max capacities.

Change-Id: I5dadac3258e18897fa3d505cf128ebe24c091efa
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>