OvmfPkg/PciHostBridgeLib: Extract InitRootBridge() / UninitRootBridge()

OvmfPkg/PciHostBridgeLib: Extract InitRootBridge() / UninitRootBridge()

Extract InitRootBridge() / UninitRootBridge() to PciHostBridgeUtilityLib
as common utility functions. No change of functionality.

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3059

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: Julien Grall <julien@xen.org>
Signed-off-by: Jiahui Cen <cenjiahui@huawei.com>
Signed-off-by: Yubo Miao <miaoyubo@huawei.com>
Message-Id: <20210119011302.10908-5-cenjiahui@huawei.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>