More robust tmp_cache dispatch (#189)

EKCache is the only AbstractODEFilterCache, and so it's safe (at least for now) to extend this function to the other algorithms. The other algorithms were fine because they were using a fallback that has been eliminated by SciML/OrdinaryDiffEq.jl#1753. It would be good to get this patch in so that the ambiguity fix PR can be fully checked.

src/alg_utils.jl

@@ -11,7 +11,7 @@ OrdinaryDiffEq.standardtag(::EK1{CS,AD,DiffType,ST}) where {CS,AD,DiffType,ST} =
 OrdinaryDiffEq.concrete_jac(::AbstractEK) = nothing
 OrdinaryDiffEq.concrete_jac(::EK1{CS,AD,DiffType,ST,CJ}) where {CS,AD,DiffType,ST,CJ} = CJ
 
-@inline DiffEqBase.get_tmp_cache(integ, alg::EK1, cache::AbstractODEFilterCache) =
+@inline DiffEqBase.get_tmp_cache(integ, alg::AbstractEK, cache::AbstractODEFilterCache) =
     (cache.tmp, cache.atmp)
 OrdinaryDiffEq.get_chunksize(::EK1{CS}) where {CS} = Val(CS)
 OrdinaryDiffEq.isfsal(::AbstractEK) = false