net: hamradio: remove support for DMA SCC devices

Another incarnation of Z8530, looks like? Again, no real changes
in the git history, and it needs VIRT_TO_BUS. Unlikely to have
users, let's spend less time refactoring dead code...

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>