cifs: prevent infinite recursion in cifs_reconnect_tcon

cifs_reconnect_tcon is called from smb_init. After a successful
reconnect, cifs_reconnect_tcon will call reset_cifs_unix_caps. That
function will, in turn call CIFSSMBQFSUnixInfo and CIFSSMBSetFSUnixInfo.
Those functions also call smb_init.

It's possible for the session and tcon reconnect to succeed, and then
for another cifs_reconnect to occur before CIFSSMBQFSUnixInfo or
CIFSSMBSetFSUnixInfo to be called. That'll cause those functions to call
smb_init and cifs_reconnect_tcon again, ad infinitum...

Break the infinite recursion by having those functions use a new
smb_init variant that doesn't attempt to perform a reconnect.

Reported-and-Tested-by: Michal Suchanek <hramrach@centrum.cz>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>