staging: et131x: Remove et131x_check_mii() and move functionality into et131x_adjust_...

staging: et131x: Remove et131x_check_mii() and move functionality into et131x_adjust_link()

et131x_check_mii() is now only being called from et131x_adjust_link.
Removed this call and associated subroutines, putting the functionality directly into et131x_adjust_link(), in preparation for further simplification.
Changed register checks from bare BMSR checks to use phydev/netif versions, also now uses adapter->link to track link state changes.

Signed-off-by: Mark Einon <mark.einon@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>