staging: rtl8712: checkpatch: Avoid multiple line dereferences

"WARNING: Avoid multiple line dereference - prefer 'poid_par_priv->information_buf_len'"
"WARNING: Avoid multiple line dereference - prefer 'padapter->registrypriv.dev_network.Configuration'"
"WARNING: Avoid multiple line dereference - prefer 'Adapter->mppriv.workparam.io_value'"

Signed-off-by: Ding-Chi Wang <dcwang.tw@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>