drm/vmwgfx: Fix the driver for large dma addresses

With dma compliance / IOMMU support added to the driver in kernel 3.13,
the dma addresses can exceed 44 bits, which is what we support in
32-bit mode and with GMR1.
So in 32-bit mode and optionally in 64-bit mode, restrict the dma
addresses to 44 bits, and strip the old GMR1 code.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Jakob Bornecrantz <jakob@vmware.com>
Cc: stable@vger.kernel.org