[BRIDGE]: Fix OOPS when bridging device without ethtool.

Bridge code calls ethtool to get speed. The conversion to using
only ethtool_ops broke the case of devices without ethtool_ops.
This is a new regression in 2.6.23.

Rearranged the switch to a logical order, and use gcc initializer.

Ps: speed should have been part of the network device structure from
    the start rather than burying it in ethtool.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Acked-by: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: David S. Miller <davem@davemloft.net>