[PATCH v1 1/1] drm: fix alpha build after drm_util.h change

[Sam Ravnborg]

Hi all.

Please do not apply.

O-DAY found a similar bug when building ia64, but this time there is
something else from irqflags.h that causes the error.

So...
> It was considered just to pull in interrupt.h but that would
> pull in a lot of unused stuff.

This seems to be the rigth solution anyway, as interrupt.h
have all the necessary dependencies.
I will try this tonight and post an updated patch.

	Sam