vsystem/taotaido.cpp: Fix player 2 controls in taotaido6 (#15879)

For a long time in `taotaidoa`, player 2's kick buttons (4-6) actually causes player 1 to kick in-game, as if they pressed their own corresponding kick buttons. The game checks player 3 and 4 inputs, which are visible in the service mode's input test program, and reuses them for kick buttons. As noted in the driver notes, players 3 and 4 aren't used at all in the 2-button parent (`taotaido`) or the 2/3-button clone ('taotaido3`). Adjusting the `P4` port to map buttons 1-3, rather than three of the directions, to player 2's buttons 4-6 allows player 2 to kick as expected.

Author: TheOpponent

src/mame/vsystem/taotaido.cpp

@@ -526,10 +526,10 @@ static INPUT_PORTS_START( taotaido6 )
 	PORT_BIT( 0xf8, IP_ACTIVE_LOW, IPT_UNKNOWN )
 
 	PORT_MODIFY("P4")
-	PORT_BIT( 0x01, IP_ACTIVE_LOW, IPT_BUTTON4 ) PORT_PLAYER(2)
-	PORT_BIT( 0x02, IP_ACTIVE_LOW, IPT_BUTTON5 ) PORT_PLAYER(2)
-	PORT_BIT( 0x04, IP_ACTIVE_LOW, IPT_BUTTON6 ) PORT_PLAYER(2)
-	PORT_BIT( 0xf8, IP_ACTIVE_LOW, IPT_UNKNOWN )
+	PORT_BIT( 0x10, IP_ACTIVE_LOW, IPT_BUTTON4 ) PORT_PLAYER(2)
+	PORT_BIT( 0x20, IP_ACTIVE_LOW, IPT_BUTTON5 ) PORT_PLAYER(2)
+	PORT_BIT( 0x40, IP_ACTIVE_LOW, IPT_BUTTON6 ) PORT_PLAYER(2)
+	PORT_BIT( 0x88, IP_ACTIVE_LOW, IPT_UNKNOWN )
 
 	PORT_MODIFY("DSW3")
 	PORT_DIPNAME( 0x08, 0x08, "Debug Info 1" )