Fix overflow in daysBeforeMonth
Fix overflow in daysBeforeMonth

The output of this method would be given in A, but of course the output could
be bigger than 255. Hence, this method would fail for October and higher, also
causing problems in convertTimeToTicks.

Fixed it now by putting the output in BC instead of A.

calcdude84se/knightos-kernel,unlimitedbacon/kernel,KnightOS/kernel,KnightOS/kernel