UNIF: Fix potential crash when accessing non-existing rom banks

- As stated, prevent a potential crash on some certain roms using split rom banks. This is done by counting the number of prg/chr banks loaded and using this as limit count during mapper bank switching.
- Update related boards.

src/boards/bmcgamecard.c

@@ -41,7 +41,7 @@ static SFORMAT StateRegs[] =
 static void Sync(void) {
 	uint8 mirroring = m350 ? ((latche >> 7) & 1) : ((latche >> 5) & 1);
 	uint8 mode      = m350 ? ((latche >> 5) & 0x03) : ((latche >> 6) & 0x03);
-	uint8 chip      = m350 ? ((mode & 2) ? ((latche >> 5) & 1) : 0) : 0;
+	uint8 chip      = m350 ? ((latche & 0x40) ? ((latche & 0x20) >> 5) : 0) : 0;
 
 	setchr8(0);
 	setprg8(0x6000, 1);