network: add the missing phy_device speed information to phy_mii_ioctl

Function `phy_mii_ioctl' returns physical device's information based on
user requests.  When requested to return the basic mode control register
information (BMCR), the original implementation only returns the physical
device's duplex information and forgets to return speed information, which
should not be because BMCR register is used to hold both duplex and speed
information.

The patch checks the BMCR value against speed-related flags and fills the
return structure's speed field accordingly.

Signed-off-by: Shan <shanlu@cs.uiuc.edu>
Cc: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>