Removes the assumption in Supported() and Start() routine that the EFI_SIO_PROTOCOL is installed in the immediate child handle of the PCI controller. Multiple SIO platform could have an additional layer between the PCI controller and the EFI_SIO_PROTOCOL instance.
Removes the assumption in Supported() and Start() routine that the EFI_SIO_PROTOCOL is installed in the immediate child handle of the PCI controller. Multiple SIO platform could have an additional layer between the PCI controller and the EFI_SIO_PROTOCOL instance.

git-svn-id: 5648d1bec6962b0a6d1d1b40eba8cf5cdb62da3d@11178 6f19259b-4bc3-4df7-8a09-765794883524

MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2