ARM: dts: am43xx-clocks: use ti, fixed-factor-clock for dpll_per_clkdcoldo

Use the ti,fixed-factor-clock version so that autoidle for
dpll_per_clkdcoldo is properly controlled after power management code
is introduced. Without this the clock may be held active even when
it is gated.

Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Tero Kristo <t-kristo@ti.com>