ALSA: emu10k1: fix access to Audigy GPIO port

ALSA: emu10k1: fix access to Audigy GPIO port

As the register definition clearly states, this is a 16-bit register,
yet we did all accesses as 32-bit. The writes in particular would have
the potential to clear the TIMER register (depending on how the bus/card
actually handles the too long writes).

This commit also introduces a separate define A_GPIO which aliases
A_IOCFG, which better reflects the distinct usage on E-MU cards.
This is done in the same commit to keep the churn down, as we're
touching all involved lines anyway.

Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Link: https://lore.kernel.org/r/20230421141006.1005539-2-oswald.buddenhagen@gmx.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>