cifs: Handle -EINPROGRESS only when noblockcnt is set

We only want to avoid blocking in connect when mounting SMB root
filesystems, otherwise bail out from generic_ip_connect() so cifs.ko
can perform any reconnect failover appropriately.

This fixes DFS failover/reconnection tests in upstream buildbot.

Fixes: 8eecd1c2 ("cifs: Add support for root file systems")
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>