We assumed that PRACH FFT size is equivalent to PxSCH FFT size.

However, the parameter ru_config->fftSize is used for the C-plane Section Type 3
which is dedicated for PRACH and mixed numerology.
Based on the PRACH format, short or long, the PRACH values 256 or 1024
shall be filled.
Co-authored-by: knopp <raymond.knopp@eurecom.fr>