[hdl] fix circular dependency for f_log2_size
gc_extend_pulse and gencores_pkg uses f_log2_size that is defined in genram. At the same time, files genrams depends on gencores_pkg. This can cause circular dependencies if common and genrams are packaged as separate cores
By using the equivalent log2_ceil function already in gencores we can break this circular dependency.
Signed-off-by: Olof Kindgren firstname.lastname@example.org