- Move IRQ functions from drm_dma.h to new drm_irq.h and disentangle them from
__HAVE_DMA. This will be useful for adding vblank sync support to sis and
tdfx. Rename dma_service to irq_handler, which is more accurately what it is.
- Fix the #if _HAVE_DMA_IRQ in radeon, r128, mga, i810, i830, gamma to have
the right number of underscores. This may have been a problem in the case
that the server died without doing its DRM_IOCTL_CONTROL to uninit