arm64: dts: add syscon for whale2 platform

Some clocks on SC9860 are in the same address area with syscon
devices, the proper syscon node will be quoted under the
definitions of those clocks in DT.

Signed-off-by: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>