Add support for PCI MGA cards to MGA DRM.

Add support for PCI MGA cards to MGA DRM.

This patch adds serveral new ioctls and a new query to get_param query to
support PCI MGA cards.

Two ioctls were added to implement interrupt based waiting.  With this change,
the client-side driver no longer needs to map the primary DMA region or the
MMIO region.  Previously, end-of-frame waiting was done by busy waiting in the
client-side driver until one of the MMIO registers (the current DMA pointer)
matched a pointer to the end of primary DMA space.  By using interrupts, the
busy waiting and the extra mappings are removed.

A third ioctl was added to bootstrap DMA.  This ioctl, which is used by the
X-server, moves a *LOT* of code from the X-server into the kernel.  This allows
the kernel to do whatever needs to be done to setup DMA buffers.  The entire
process and the locations of the buffers are hidden from user-mode.

Additionally, a get_param query was added to differentiate between G4x0 cards
and G550 cards.  A gap was left in the numbering sequence so that, if needed,
G450 cards could be distinguished from G400 cards.  According to Ville
Syrjälä, the G4x0 cards and the G550 cards handle anisotropic filtering
differently.  This seems the most compatible way to let the client-side driver
know which card it's own.  Doing this very small change now eliminates the
need to bump the DRM minor version twice.

http://marc.theaimsgroup.com/?l=dri-devel&m=106625815319773&w=2

(airlied - this may not work at this point, I think the follow on buffer
 cleanup patches will be needed)

From: Ian Romanick <idr@us.ibm.com>
Signed-off-by: Dave Airlie <airlied@linux.ie>