typo: virtio-gpu: contignous -> contiguous

[hernejj]

In Virtio-1.10 spec the section is 5.7.6.1 Device Operation: Create a framebuffer and configure scanout

Allocate a framebuffer from guest ram, and attach it as backing storage to the resource just created, using
VIRTIO_GPU_CMD_RESOURCE_ATTACH_BACKING. Scatter lists are supported, so the framebuffer doesn’t
need to be contignous in guest physical memory.