smb3: improve handling of share deleted (and share recreated)

When a share is deleted, returning EIO is confusing and no useful
information is logged.  Improve the handling of this case by
at least logging a better error for this (and also mapping the error
differently to EREMCHG).  See e.g. the new messages that would be logged:

[55243.639530] server share \\192.168.1.219\scratch deleted
[55243.642568] CIFS VFS: \\192.168.1.219\scratch BAD_NETWORK_NAME: \\192.168.1.219\scratch

In addition for the case where a share is deleted and then recreated
with the same name, have now fixed that so it works. This is sometimes
done for example, because the admin had to move a share to a different,
bigger local drive when a share is running low on space.

Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>