wifi: rtw88: rtw8821c: Implement RTL8821CS (SDIO) efuse parsing

The efuse of the SDIO RTL8821CS chip has only one known member: the mac
address is at offset 0x11a. Add a struct rtw8821cs_efuse describing this
and use it for copying the mac address when the SDIO bus is used.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Reviewed-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230218152944.48842-4-martin.blumenstingl@googlemail.com