vmwgfx: Rework device initialization

This commit reworks device initialization so that we always enable the
FIFO at driver load, deferring SVGA enable until either first modeset
or fbdev enable.
This should always leave the fifo properly enabled for render- and
control nodes.
In addition,
*) We disable the use of VRAM when SVGA is not enabled.
*) We simplify PM support so that we only throw out resources on hibernate,
not on suspend, since the device keeps its state on suspend.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>