wifi: rtw89: add EHT capabilities for WiFi 7 chips

The coming WiFi 7 chip 8922A will support EHT, so declare EHT along with
hardware capabilities.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20240112062640.36922-4-pkshih@realtek.com