enic: do notify_check before returning credits

We should complete notify_check before returning the credits. Once we return the
credits, adaptor may access the notify data.

Signed-off-by: Sujith Sankar <ssujith@cisco.com>
Signed-off-by: Govindarajulu Varadarajan <_govind@gmx.com>
Signed-off-by: David S. Miller <davem@davemloft.net>