uper_encode_to_buffer() of asn1c returns the number of BITS that have
been encoded; if we use this, we need to calculate the resulting number
of bytes (rounding up) to get the right buffer size.

Note that do_NR_ULInformationTransfer() uses
uper_encode_to_new_buffer() which returns the number of BYTES, hence, in
this similar function, we should not modify the return value.