net: dl2k: remove redundant re-assignment to np

The pointer np is initialized and then re-assigned the same value
a few lines later. Remove the redundant duplicated assignment. Cleans
up clang warning:

drivers/net/ethernet/dlink/dl2k.c:314:25: warning: Value stored to
'np' during its initialization is never read

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>