s390/qeth: don't restrict qeth_card to DMA memory

Allocating the main qeth_card struct with GFP_DMA blocks us from moving
it into netdev_priv(). But the only reason why we need DMA memory is the
ccw1 structs embedded into each ccw channel. So extract those into
separate allocations, like we already do for the cmd buffers.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>