dt-bindings: clock: brcm,iproc-clocks: fix armpll properties

dt-bindings: clock: brcm,iproc-clocks: fix armpll properties

armpll clocks (available on Cygnus and Northstar Plus) are simple clocks
with no cells. Adjust binding props #clock-cells and clock-output-names
to handle them.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Link: https://lore.kernel.org/r/20210819052918.6753-1-zajec5@gmail.com
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>