Hyundai CAN-FD: common PT bus function cleanup (#27397)

* Hyundai CAN-FD: common PT bus function cleanup

* use CP

* Update selfdrive/car/hyundai/hyundaicanfd.py

---------

Co-authored-by: Shane Smiskol <shane@smiskol.com>
old-commit-hash: a20f07144b

selfdrive/car/hyundai/interface.py

@@ -2,6 +2,7 @@
 from cereal import car
 from panda import Panda
 from common.conversions import Conversions as CV
+from selfdrive.car.hyundai.hyundaicanfd import get_e_can_bus
 from selfdrive.car.hyundai.values import HyundaiFlags, CAR, DBC, CANFD_CAR, CAMERA_SCC_CAR, CANFD_RADAR_SCC_CAR, EV_CAR, HYBRID_CAR, LEGACY_SAFETY_MODE_CAR, Buttons
 from selfdrive.car.hyundai.radar_interface import RADAR_START_ADDR
 from selfdrive.car import STD_CARGO_KG, create_button_event, scale_tire_stiffness, get_safety_config
@@ -247,8 +248,7 @@ class CarInterface(CarInterfaceBase):
 
     # *** feature detection ***
     if candidate in CANFD_CAR:
-      bus = 5 if ret.flags & HyundaiFlags.CANFD_HDA2 else 4
-      ret.enableBsm = 0x1e5 in fingerprint[bus]
+      ret.enableBsm = 0x1e5 in fingerprint[get_e_can_bus(ret)]
     else:
       ret.enableBsm = 0x58b in fingerprint[0]