So far we used to store the sums of ToA and RSSI measurements in the
logical channel state, and after decoding of a block, we did calculate
the average. This approach works fine for xCCH and PDTCH, but when it
comes to block-diagonal interleaving (which is used on TCH/F and TCH/H
channels), the results are incorrect. The problem is that a burst on
TCH may carry 57 bits of one encoded frame and 57 bits of another.
Instead of calculating the sum of measurements on the fly, let's push
them into a circular buffer (the measurement history), and keep them
there even after decoding of a block. This would allow us to calculate
the average of N last measurements depending on the interleaving type.
A single circular buffer can hold up to 8 unique measurements, so the
recent measurements would basically override the oldest ones.
Change-Id: I211ee3314f0a284112a4deddc0e93028f4a27cef