PM: EM: Refactor em_adjust_new_capacity()

Extract em_table_dup() and em_recalc_and_update() from
em_adjust_new_capacity(). Both functions will be later reused by the
'update EM due to chip binning' functionality.

Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>