staging: rtl8192e: GetTs Fix invalid TID 7 warning.

commit 95d93e271d920dfda369d4740b1cc1061d41fe7f upstream.

TID 7 is a valid value for QoS IEEE 802.11e.

The switch statement that follows states 7 is valid.

Remove function IsACValid and use the default case to filter
invalid TIDs.

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>