MdeModulePkg: Update UNI file for PCIe Resizable BAR Capability

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3138

PcdPcieResizableBarSupport was added in MdeModulePkg.dec, update
UNI file as the documentation of the PCD.

Cc: Ray Ni <ray.ni@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Signed-off-by: Heng Luo <heng.luo@intel.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Acked-by: Hao A Wu <hao.a.wu@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
1 file changed