tg3: Remove unneeded link_config.orig_... members

This patch removes the unneeded link_config.orig_* members.  When the
phy is in a low power state, the TG3_PHYFLG_IS_LOW_POWER flag solely
determines how the link is configured.  When the phy is powered back up,
it can resume using the original settings.

For the phylib case, the link configuration still needs to be saved, but
since the phylib maintains its own configuration, we can repurpose the
(unused in this case) tg3 link configuration members.

Signed-off-by: Matt Carlson <mcarlson@broadcom.com>
Reviewed-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>