drm/vmwgfx: Fix framebuffer creation on older hardware

On older hardware, texture max width and height is not available, so set
it to something reasonable, like 8192.

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

diff --cc drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
Simple merge