Revert "Made hidl_vec(size_t size) explicit"

This reverts commit f7e10f4a46ab6343b72d0a1e948d029a6a8be3ba.
That commit broke several builds.

I suspect that an implicit conversion now made explicit has exposed
several issues where a hidl_vec not was constructed correctly, but not
entirely sure.

Test: That it builds
1 file changed