trau_frame: Fix computation of odd parity while encoding HR frames
trau_frame: Fix computation of odd parity while encoding HR frames

division modulo 1 is always 0, and hence we always returned '1'
as parity bit.  Instead, we need to check if the LSB is set in order to
know if the number of bits is odd or even.

Change-Id: I37af702ba020a90a820bae84cb603e187ebbacb5
Closes: CID#211594

osmocom/libosmo-abis,osmocom/libosmo-abis,osmocom/libosmo-abis