MdeModulePkg: Fix a PciBusDxe hot plug bug

MdeModulePkg: Fix a PciBusDxe hot plug bug

For a hot plug bridge with device attached, PciBusDxe driver reserves
the resources which equal to the total amount of padding resource
returned from HotPlug->GetResourcePadding() and the actual occupied
resource by the attached device. The behavior is incorrect.
Correct behavior is to reserve the bigger one between the padding
resource and the actual occupied resource.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Reviewed-by: Feng Tian <feng.tian@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18719 6f19259b-4bc3-4df7-8a09-765794883524