OvmfPkg: PciHostBridgeDxe: release resources on driver entry failure

OvmfPkg: PciHostBridgeDxe: release resources on driver entry failure

The entry point of the driver, InitializePciHostBridge(), leaks resources
(and installed protocols) in the following cases:

- The first root bridge protocol installation fails. In this case, the
  host bridge protocol is left installed, but the driver exits with an
  error.

- The second or a later root bridge protocol installation fails. In this
  case, the host bridge protocol, and all prior root bridge protocols, are
  left installed, even though the driver exits with an error.

Handle errors correctly: roll back / release / uninstall resources when
aborting the driver.

Cc: Jordan Justen <jordan.l.justen@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Regression-tested-by: Gabriel Somlo <somlo@cmu.edu>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17959 6f19259b-4bc3-4df7-8a09-765794883524