Fu Hanxi f04a0cc526 fix: bypass Manually-specified variables were not used by the project warning
the variable "IDF_TARGET" is only used under a if clause
"if(ULP_C0CPU_IS_RISCV)". while building a non-riscv target,
there will be a cmake warning:

CMake Warning:
  Manually-specified variables were not used by the project:

    IDF_TARGET
2022-07-14 08:26:01 +08:00
..