panfrost: Allocate polygon lists on-demand

panfrost: Allocate polygon lists on-demand

Rather than alloacting a huge (64MB) polygon list on context creation
and sharing it across framebuffers, we instead allocate polygon lists as
BOs (which consistently hit the cache) sized appropriately; for about a
month, we've known how to calculate the polygon list size so this has
only recently become possible.

The good news is we can render to truly massive framebuffers without
crashing and, more importantly, we eliminate the 64MB upfront overhead.
If a list that size isn't actually needed, it's not allocated.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>