ibm_newemac: PowerPC 440EP/440GR EMAC PHY clock workaround

ibm_newemac: PowerPC 440EP/440GR EMAC PHY clock workaround

This patch adds ibm_newemac PHY clock workaround for 440EP/440GR EMAC
attached to a PHY which doesn't generate RX clock if there is no link.
The code is based on the previous ibm_emac driver stuff. The 440EP/440GR
allows controlling each EMAC clock separately as opposed to global clock
selection for 440GX.

BenH: Made that #ifdef CONFIG_PPC_DCR_NATIVE for now as dcri_* stuff doesn't
exist for MMIO type DCRs like Cell. Some future rework & improvements of the
DCR infrastructure will make that cleaner but for now, this makes it work.

Signed-off-by: Valentine Barshak <vbarshak@ru.mvista.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>