ARM: dts: arm: Fix SP804 users

ARM: dts: arm: Fix SP804 users

The SP804 DT nodes for Realview, MPS2 and VExpress were not complying
with the binding: it requires either one or three clocks, but does not
allow exactly two clocks.

Simply duplicate the first clock to satisfy the binding requirement.
For MPS2, we triple the clock, and add the clock-names property, as this
is required by the Linux primecell driver.
Try to make the clock-names more consistent on the way.

Link: https://lore.kernel.org/r/20200828142018.43298-3-andre.przywara@arm.com
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>