[position_calc] g_IQ_width generic seems unnecessary

[lerwys]

Problem: g_IQ_width is used just to resize the Mixer output word to another number of bits. This parameter is already controlled via g_mixed_width.

We used to want this resize as the mixed width was 24 bits, and 24 (bits) *8 (A/B/C/D I/Q) = 192, which is not a power of 2 and would need to be aligned for the acquisition module.

This poses a problem as we are wasting bandwidth.