dbc: Add details for SBW (Shift Select Switch)

From bench experiments, see also
https://github.com/projectgus/car_hacking/blob/main/hyundai_kona_ev/shift_select_switch.py

dbc/hyundai_kona.dbc

@@ -72,9 +72,10 @@ BO_ 688 SAS11: 5 XXX
  SG_ MsgCount : 32|4@1+ (1,0) [0|15] "" XXX
  SG_ CheckSum : 36|4@1+ (1,0) [0|15] "" XXX
 
-BO_ 852 UNK_354: 8 XXX
- SG_ GEAR_SELECT_MOMENTARY : 0|24@1+ (1,0) [0|16777215] "" XXX
- SG_ DUAL_COUNTER : 56|8@1+ (1,0) [0|255] "" XXX
+BO_ 852 SBW_354: 8 XXX
+ SG_ Button_Pressed : 7|24@0+ (1,0) [0|16777215] "" XXX
+ SG_ Gear_Displayed : 40|8@1+ (1,0) [0|255] "" XXX
+ SG_ Counter : 56|8@1+ (1,0) [0|255] "" XXX
 
 BO_ 902 WHL_SPD11: 8 XXX
  SG_ WHL_SPD_FL : 0|14@1+ (0.03125,0) [0|511.96875] "km/h" XXX
@@ -600,12 +601,14 @@ BO_ 3221225472 VECTOR__INDEPENDENT_SIG_MSG: 0 XXX
  SG_ CF_Fatc_CtrInf : 0|3@1+ (1,0) [0|7] "" XXX
  SG_ CF_Fatc_MsgCnt : 0|4@1+ (1,0) [0|15] "" XXX
 
+CM_ BO_ 852 "Shift Select Switch";
 CM_ SG_ 1431 Active "This bit set when vehicle is in Ready, or Charging";
 CM_ SG_ 1433 CCS_CHARGE_TRIGGER "Might indicate contactors closed?";
 CM_ SG_ 1433 CCS_error_ack "Seems to go high to "ack" the CCS_CCM_error bit from CCM";
 CM_ SG_ 1438 UNK_U_HV "Maps to 595 UBatt, maybe voltage at another point?";
 VAL_ 512 CURRENT_GEAR 0 "P" 5 "D" 6 "N" 7 "R";
 VAL_ 3221225472 CF_VSM_Warn 2 "FCW" 3 "AEB";
+VAL_ 852 Gear_Displayed 0 "None" 1 "P" 2 "R" 3 "N" 4 "D";
 VAL_ 3221225472 CF_Lvr_Gear 5 "D" 8 "S" 6 "N" 7 "R" 0 "P";
 VAL_ 3221225472 ACCMode 0 "off" 1 "enabled" 2 "driver_override" 3 "off_maybe_fault" 4 "cancelled";
 VAL_ 3221225472 Elect_Gear_Shifter 5 "D" 8 "S" 6 "N" 7 "R" 0 "P";