wifi: rtl8xxxu: Fix assignment to bit field priv->cck_agc_report_type

Just because priv->cck_agc_report_type is only one bit doesn't mean
it works like a bool. The value assigned to it loses all bits except
bit 0, so only assign 0 or 1 to it.

This affects the RTL8192EU, but rtl8xxxu already can't connect to any
networks with this chip, so it probably didn't bother anyone.

Fixes: 2ad2a813 ("wifi: rtl8xxxu: Fix the CCK RSSI calculation")
Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Reviewed-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/7bb4858c-5cef-9cae-5e08-7e8444e8ba89@gmail.com