write_zsreg - Write to a Z8530 channel register
void write_zsreg (struct z8530_channel * c, u8 reg, u8 val);
c The Z8530 channel reg Register number val Value to write
Write a value to an indexed register. The caller must hold the lock to honour the irritating delay rules. We know about register 0 being fast to access. Assumes c->lock is held.
Alan Cox <email@example.com>.