fixup... remove another Requires'ism

Author: samtkaplan

ext/MPIExt.jl

@@ -10,9 +10,6 @@ import Devito: localmask, localmask_with_halo, localmask_with_inhalo, decomposit
 import Devito: localindices, localindices_with_halo, localindices_with_inhalo
 import Devito: data_allocated, data, data_with_halo, data_with_inhalo
 
-isdefined(Base, :get_extension) ? (using MPI) : (using ..MPI)
-
-
 abstract type DevitoMPIAbstractArray{T,N} <: AbstractArray{T,N} end
 
 Base.parent(x::DevitoMPIAbstractArray) = x.p