MdeModulePkg/PciHostBridgeDxe: remove unused but set variables

MdeModulePkg/PciHostBridgeDxe: remove unused but set variables

Remove variables that are declared, assigned but never referenced. This
fixes a warning emitted by GCC when -Wunused-but-set-variable is in effect.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Feng Tian <feng.tian@intel.com>
Reviewed-by: Jeff Fan <jeff.fan@intel.com>