Changes

csd_v110: set E2 bit correctly for TCH/F4.8 NT

In all classic NT modes below 14.5 kbit/s, V.110 frame bits E2 and E3
are repurposed to indicate the alignment whereby a single 240-bit RLP
frame is composed of 4 pseudo-V.110 frames in switching transport.
(TS 48.020 section 15.1.)  In the case of TCH/F9.6, setting both E2
and E3 is easy because all 4 pseudo-V.110 frames go out in the same
clearmode RTP packet as a result of a single channel decoding
operation.  However, in the case of TCH/F4.8 there are two separate
channel decoding operations producing two separate RTP packets
20 ms apart.  Furthermore, GSM 05.03 section 3.4.1 specifies which
TDMA frame positions hold which half of the RLP frame - therefore,
the correct emission of bit E2 needs to be based on the TDMA frame
number at which the block was received.

Related: OS#6578
Change-Id: I1e0ad58aad3361b3a2b0a47113bd065587636730