Bluetooth: btqcomsmd: Fix rx/tx stats

HCI RX/TX byte counters were only incremented when sending ACL packets.
To reflect the real HCI traffic, we need to increment these counters on
HCI events and HCI commands as well.

Increment error counter on rpmsg errors.

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>