cmake: remove clang++ lookup in clang/generic.cmake

Fixes: #63771

The 'compiler/*/generic.cmake' is intended to set a C preprocessor which
can be used for devicetree preprocessing.

No C++ compiler is needed as host tool and should therefore not be set
in this file.

Remove the code to avoid setting a not required C++ compiler.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>

cmake/compiler/clang/generic.cmake

@@ -5,7 +5,6 @@ if(DEFINED TOOLCHAIN_HOME)
 endif()
 
 find_program(CMAKE_C_COMPILER clang ${find_program_clang_args} REQUIRED)
-find_program(CMAKE_CXX_COMPILER clang++ ${find_program_clang_args})
 find_program(CMAKE_LLVM_COV llvm-cov ${find_program_clang_args})
 set(CMAKE_GCOV "${CMAKE_LLVM_COV} gcov")