rtlwifi: Add ratr_table for newer IC

New generation ICs will support 11ac, 5G, n-NSS, etc, so we define a set of
rate ID.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>