hamradio: 6pack: remove unnecessary check

this is check for dev is unnecessary, as we are already checking dev
after allocating it via alloc_netdev, and jumping to label: out
if it is NULL.

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: David S. Miller <davem@davemloft.net>