ARM: dts: Fix dcan clkctrl clock for am3

We must not use legacy clock defines for dts clckctrl clocks as the offsets
will be wrong.

Fixes: 87fc89ce

 ("ARM: dts: am335x: Move l4 child devices to probe them with ti-sysc")
Cc: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>