ARM: dts: bcm283x: Remove simple-bus from fixed clocks

ARM: dts: bcm283x: Remove simple-bus from fixed clocks

The fixed clocks doesn't form some kind of bus. So let's remove it.
This fixes the follow DT schema warnings:

clocks: clock@3:reg:0: [3] is too short
clocks: clock@4:reg:0: [4] is too short
clocks: $nodename:0: 'clocks' does not match '^(bus|soc|axi|ahb|apb)(@[0-9a-f]+)?$'
clocks: #size-cells:0:0: 0 is not one of [1, 2]
clocks: 'ranges' is a required property
clock@3: 'reg' does not match any of the regexes: 'pinctrl-[0-9]+'
clock@4: 'reg' does not match any of the regexes: 'pinctrl-[0-9]+'

Signed-off-by: Stefan Wahren <wahrenst@gmx.net>