Revert "arm64: dts: Add support for Unisoc's UMS512"
The patch uses the "dt-bindings/clock/sprd,ums512-clk.h header, which
is not merged yet. This caused a build regression, and it means the
patch was not ready to get merged anyway.
This reverts commit 23410de5796cd49abb3f9b6d377822e18298e0a0.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>