virgl: use virgl_transfer_inline_write even less

virgl: use virgl_transfer_inline_write even less

We've noticed the Team Fortress 2 engine seems to do many small
calls to glSubData(..). Let's pick our heuristic based on the
resource base width, not the size of a particular upload.
This will cause transfers to be batched together in the transfer
queue.

Revelant glbench microbenchmark --

Before: buffer_upload_dynamic_element_array_131072 = 131.17 mbytes_sec
After: buffer_upload_dynamic_element_array_131072 = 6828.24 mbytes_sec
Reviewed-by: Gert Wollny <gert.wollny@collabora.com>