1) Change Framework version of PeiServiceTable's PciCfg from PEI_PCI_CFG_PPI to ECP_P...

1) Change Framework version of PeiServiceTable's PciCfg from PEI_PCI_CFG_PPI to ECP_PEI_PCI_CFG_PPI. This help to detect if user is calling PeiServiceTable->PciCfg->Modify in a PI platform. Modify between Framework spec and PI spec is not compatible.
2) Add ECP_PEI_PCI_CFG_PPI to EdkFrameworkPpiLib
3) Add PeiLibPciCfgModify which call PciCfg2. This function will used by modified Framework Module which will be working with a PI platform.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@5260 6f19259b-4bc3-4df7-8a09-765794883524