staging: et131x: Fix et131x smatch issues

This fixes the following issues:

et131x_initpci.c +488 et131x_adjust_link(45) error: we previously assumed 'phydev' could be null.
et131x_initpci.c +504 et131x_adjust_link(61) warn: variable dereferenced before check 'phydev'

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