board-latona-display: remove OCP interconnect constraints

L3 OPP1 is disabled, there's no need to specify constraints.
board-latona-display: code cleanup

Remove useless function, declare init_clk_disable as static and
fix code indentation.
Merge branch 'latona-3.0.y-backports' into latona-3.0.y
Merge branch 'latona-3.0.y-interactive' into latona-3.0.y
Merge branch 'latona-3.0' into latona-3.0.y