iwlwifi: mvm: change TX/RX AM-to-PSM transition time for LP mode

Recently in low power (LP) mode FW moved from active to power save mode
after TX/RX completion faster than in balanced power mode (BPS).
Change AM-to-PSM transition time so that it will be the same as for BPS.

Signed-off-by: Alexander Bondar <alexander.bondar@intel.com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>