ARM: dts: clps711x: Add an empty chosen node to top level DTSI

Missing "chosen" node can cause issues when booting a kernel
with a boot-loader that doesn't create a chosen node if this
isn't present in the DTB since the decompressor relies on a
pre-existing chosen node to be available to insert the command
line and merge other ATAGS info.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Link: https://lore.kernel.org/r/20210405051658.26779-5-shc_work@mail.ru

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Signed-off-by: Arnd Bergmann <arnd@arndb.de>