This chapter takes precedence over any conflicting provisions contained in section 535.8, subsection 4, with respect to the use or enforcement of a due-on-sale or similar clause in a mortgage loan agreement, and takes precedence over any conflicting provisions contained in laws enacted after July 1, 1981, with respect to the use or enforcement of a due-on-sale or similar clause in a mortgage loan agreement unless those laws expressly provide that they take precedence over this chapter.