s4:torture: Initialize union smb_open

s4:torture: Initialize union smb_open

"Error: UNINIT (CWE-457):
samba-4.20.0rc2/source4/torture/raw/open.c:1136: var_decl: Declaring variable ""io1"" without initializer.
samba-4.20.0rc2/source4/torture/raw/open.c:1198: uninit_use_in_call: Using uninitialized value ""io1.ntcreatex.out.file.fnum"" when calling ""smbcli_close"".
 1196|    done:
 1197|   	smbcli_close(cli->tree, io.ntcreatex.out.file.fnum);
 1198|-> 	smbcli_close(cli->tree, io1.ntcreatex.out.file.fnum);
 1199|   	smbcli_deltree(cli->tree, BASEDIR);
 1200|   	return ret;"

Signed-off-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Guenther Deschner <gd@samba.org>