Use singleton instance of TargetService in mmio.C
Use singleton instance of TargetService in mmio.C

There is a bug in the function that looks up the targeting service.
It is calling the constructor when it should just call the function
that looks up the singleton object.

Change-Id: I5ea91736e85c84927e3e0fe74352f61326e42940
Reviewed-on: http://rchgit01.rchland.ibm.com/gerrit1/71209
Tested-by: Jenkins Server <8e3f934e4c44875bc48d33da3ea13d93ba9a233f@us.ibm.com>
Tested-by: Jenkins OP Build CI <e610bd72261d3c0a48f1e8ae36832ab00774d426@us.ibm.com>
Tested-by: FSP CI Jenkins <aa9e4d9ac7cd25905e9c0dd36d4150516e73dd86@us.ibm.com>
Tested-by: Jenkins OP HW <0eb0fff262f74a65a832afbcc7b153e391c9a3fd@us.ibm.com>
Reviewed-by: Matt Derksen <7e9f2fc2ed13c4ee3c2ab17f188630a0f557de86@us.ibm.com>
Reviewed-by: Corey V. Swenson <6b585c7446d4a0351ef146912eaabcae3d9a2e28@us.ibm.com>
Reviewed-by: Daniel M. Crowell <912029ca9254ac7b5854e56910561d682e1fa2d0@us.ibm.com>

open-power/hostboot,open-power/hostboot,open-power/hostboot,open-power/hostboot,open-power/hostboot