Many ARM SoCs included <devicetree.h> likely due to:
1. nvic.h not being self-contained
2. As a result of copy-paste
Some RISC-V SoCs had the same problem, in this case likely due to
copy-paste from ARM. The <devicetree.h> header has been removed using
the following command:
sed -i ':a;N;$!ba;s/#include <devicetree\.h>\n//g' soc/**/soc.h
soc.h files that make a legitimate usage of the API have not been
changed.
Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>