[CUDA][HIP] ignore implicit host/device attr for override (#72815)

When deciding whether a previous function declaration is an overload or
override, implicit host/device attrs should not be considered.

This fixes the failure for the following code:

`template <typename T>
class C {
    explicit C() {};
};

template <> C<int>::C() {};
`

The issue was introduced by
https://github.com/llvm/llvm-project/pull/72394

sine the template specialization is treated as overload due to implicit
host/device attrs are considered for overload/override differentiation.