net: Only call halt on a driver that has been init'ed

net: Only call halt on a driver that has been init'ed

With driver model, we were not checking if the state of the device was
marked as active before calling the halt function. Check that the device
is probed and also marked as active. This avoids the case where we were
calling halt on the first device in net_init() and the driver would
operate on bogus data structures causing problems. In this case, the
priv was all 0, so halt() would close STDIN.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: Simon Glass <sjg@chromium.org>