Fixed an issue with operator precedence in calls to `send_byte()`, in
which a value of `1` was being sent to the function. This had the
nasty side-effect of selecting the slave drive if the value of
`head` was equal to one. A read/write would fail in the case, as
it would attempt to read from the slave drive (not good).
I've also added a seek to the top of the read/write code, which seems
to have fixed an issue with Linux not detecting the disk images after
they have been unmounted from Serenity. This isn't specified in the
datasheet, but a few other drivers have it so we should too :^)
c12d153894