usbnet: smsc95xx: add reset_resume function with reset operation

The smsc95xx needs to resume with reset operation. Otherwise it causes
system hang by network error like below after resume. This case appears
on odroid u3 board.

[    9.727600] smsc95xx 1-2:1.0 eth0: kevent 2 may have been dropped
[    9.727648] smsc95xx 1-2:1.0 eth0: kevent 2 may have been dropped
[    9.727689] smsc95xx 1-2:1.0 eth0: kevent 2 may have been dropped
[    9.727728] smsc95xx 1-2:1.0 eth0: kevent 2 may have been dropped
[    9.729486] PM: resume of devices complete after 2011.219 msecs
[   10.117609] Restarting tasks ... done.
[   11.725099] smsc95xx 1-2:1.0 eth0: kevent 2 may have been dropped
[   13.480846] smsc95xx 1-2:1.0 eth0: kevent 2 may have been dropped
[   13.481361] smsc95xx 1-2:1.0 eth0: kevent 2 may have been dropped
...

Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: David S. Miller <davem@davemloft.net>