ucc_geth: fixes for ucc_geth_memclean

The ucc_geth_memclean function can be called before the Tx BD rings, Rx
BD rings and associated socket buffers are allocated (for example if
ucc_fast_init fails). The current code doesn't check if p_tx_bd_ring[i]
is null, generating a kernel panic when trying to free the associated
socket buffers.

The function can also fail when accessing the uninitialized list_head
structures ugeth->group_hash_q and ugeth->ind_hash_q. In the current
implementation the list heads are initialized only when
maxGroupAddrInHash and maxIndAddrInHash are positive values, although I
think it's better to always initialize them.

Signed-off-by: Ionut Nicu <ionut.nicu@freescale.com>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>