drm/i915: Use a DRM-managed action to release the PCI bridge device

As we start supporting multiple uncore structures in future patches, the
MMIO cleanup (which may also get called mid-init if there's a failure)
will become more complicated.  Moving to DRM-managed actions will help
keep things simple.

Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220906234934.3655440-8-matthew.d.roper@intel.com
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>