ALSA: uapi: Make alsa asound.h header more portable

This header is used as-is in the alsa-lib userland library,
which is portable to other operating systems.
For this reason, include linux/types.h only on Linux systems.

Add sys/ioctl.h for _IOR/_IOW/etc. (works at least on *BSD and Solaris).

Signed-off-by: Thomas Klausner <wiz@NetBSD.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>