reverting the changes present in 29017 as CFLAGS and CXXFLAGS which overrides defaults in other packages (#30036)

var/spack/repos/builtin/packages/llvm-amdgpu/package.py

@@ -112,12 +112,6 @@ class LlvmAmdgpu(CMakePackage):
         when='@master +rocm-device-libs'
     )
 
-    def setup_dependent_build_environment(self, env, dependent_spec):
-        # LLVM-amdgpu is always based off of a pre-release version of LLVM.
-        # Set the version suffix to denote this fact for downstream projects.
-        env.append_flags('CXXFLAGS', '-DLLVM_VERSION_SUFFIX=git')
-        env.append_flags('CFLAGS', '-DLLVM_VERSION_SUFFIX=git')
-
     def cmake_args(self):
         llvm_projects = [
             'clang',