dev/sound/pcm/sound.h shadows INTR_MPSAFE declaration

[Yuriy Tsibizov]

> > Today I've noticied that my driver is marked as Giant-locked:
> 
> Is it actually MPSAFE?  If so, feel free to mark it as such, 
> although pcm
> isn't fully locked yet, so we take no responsibility for any damage
> caused :)

Some sound drivers in -CURRENT allocate interrupts with INTR_MPSAFE. 
The problem is that after including dev/sound/pcm/sound.h INTR_MPSAFE no longer equals to 512, but it is set to 0. And if sound driver interrupt was allocated as INTR_TYPE_AV|INTR_MPSAFE it will be marked only as INTR_TYPE_TTY. 

Yuriy.