freedreno: Try to look up handle in table in fd_bo_from_dmabuf()

This is to avoid creating duplicate BO struct on multiple calls to
fd_bo_from_dmabuf() with the same file descriptor.

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
freedreno: Use prime helpers instead of ioctls directly

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
freedreno: Let bo_from_handle callback override null size

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>