ucc_geth: Pass proper device to DMA routines, otherwise oops happens

The driver should pass a device that actually specifies internal DMA
ops, but currently it passes netdev's device, which is wrong and that
causes following oops:

Kernel BUG at c01c4df8 [verbose debug info unavailable]
Oops: Exception in kernel mode, sig: 5 [#1]
[...]
NIP [c01c4df8] get_new_skb+0x7c/0xf8
LR [c01c4da4] get_new_skb+0x28/0xf8
Call Trace:
[ef82be00] [c01c4da4] get_new_skb+0x28/0xf8 (unreliable)
[ef82be20] [c01c4eb8] rx_bd_buffer_set+0x44/0x98
[ef82be40] [c01c62bc] ucc_geth_startup+0x11b0/0x147c
[ef82be80] [c01c6674] ucc_geth_open+0xec/0x2a4
[ef82bea0] [c02288a4] dev_open+0xc0/0x11c
[...]

Fix this by passing of_device's device that specifies DMA ops in its
archdata.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: David S. Miller <davem@davemloft.net>