Add the rx_number_packets and rx_number_bits in Bluetooth Rx API.

There are 3 kinds of packet type in Bluetooth testing: BDR, EDR, and
LE. We measure packet error rate in LE, and measure bit error rate in
BDR and EDR. Therefore we need the number of transmitted packets in
LE, otherwise the number of transmitted bits. Add these two arguments
in each Bluetooth Rx API with default value "None".

BUG=chromium:681734
TEST=make test

Change-Id: I3fd5abec604f6e4f9f6956846f14133403713e05
Reviewed-on: https://chromium-review.googlesource.com/428478
Commit-Ready: Chih-Yu Huang <akahuang@chromium.org>
Tested-by: Chih-Yu Huang <akahuang@chromium.org>
Reviewed-by: Joel Kitching <kitching@chromium.org>
2 files changed