Merge changes I05ccdb3e,I00065f65,I2310c69c,I8832601e,I55ec884b, ...

* changes:
  enum-ify stack/btm/btm_ble_int_types::tBTM_BLE_SEC_REQ_ACT
  enumify tL2C_CB::tL2C_LCB::conn_update_mask
  Remove unnecesary warning on expected parsing failure
  Only read power mode on non-le links
  Add helpers tL2C_CB::tL2C_LCB::tBT_TRANSPORT
  Streamline stack/l2cap/l2c_link::l2c_link_check_power_mode
  Internally link stack/l2cap/l2c_link::l2c_link_check_power_mode
  Remove def stack/l2cap/l2c_link::L2C_LINK_CHECK_POWER_MODE
  Slight cleanup stack/acl/btm_pm::BTM_SetSsrParams
  Specialize data structures tBTM_PM_STATUS tBTM_PM_MODE