CodeGen: Move getAddressSpaceForPseudoSourceKind into TargetMachine

Avoid the dependency on TargetInstrInfo, which depends on the subtarget
and therefore the individual function.

Currently AMDGPU is constructing PseudoSourceValue instances in MachineFunctionInfo.
In order to facilitate copying MachineFunctionInfo, we need to stop allocating these
there. Alternatively we could allow targets to subclass PseudoSourceValueManager,
and allocate them similarly to MachineFunctionInfo.