enic: Use a lighter reset operation for enic devices

The port profile information for a dynamic enic device is set by the upper
layers, that are oblivious to the device reset operation. We do not want a
reset operation erase the network state of a dynamic enic device as there
is no way to set up the port profile information again. Hence a lighter
reset operation called hang reset is used. Hang reset, unlike soft reset
does not reset the network state and resets the host side state only.

Signed-off-by: Scott Feldman <scofeldm@cisco.com>
Signed-off-by: Vasanthy Kolluri <vkolluri@cisco.com>
Signed-off-by: Roopa Prabhu <roprabhu@cisco.com>
Signed-off-by: David S. Miller <davem@davemloft.net>