ALSA: aoa: Replace asm/prom.h with explicit includes

asm/prom.h should not be included directly as it no longer contains
anything drivers need. Drivers should include of.h and/or other headers
which were getting implicitly included.

Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20231003163209.770750-1-robh@kernel.org


Signed-off-by: Takashi Iwai <tiwai@suse.de>