MdeModulePkg/PciBus: Count multiple hotplug resource paddings

MdeModulePkg/PciBus: Count multiple hotplug resource paddings

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=720

The current implementation assumes there is only one hotplug resource
padding for each resource type. It's not true considering
DegradeResource(): MEM64 resource could be degraded to MEM32
resource.

The patch treat the resource paddings using the same logic as
treating typical/actual resources and the total resource of a bridge
is set to the MAX of typical/actual resources and resource paddings.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>