ravb: Fix up dma_free_coherent() call in ravb_remove()

In ravb_remove(), dma_free_coherent() should be call after
unregister_netdev(). Otherwise, this controller is possible to use
the freed buffer.

Fixes: c156633f ("Renesas Ethernet AVB driver proper")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Link: https://lore.kernel.org/r/20231005011201.14368-2-yoshihiro.shimoda.uh@renesas.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>