drm/xe/irq: remove xe_irq_shutdown

The cleanup is done by devres in irq_uninstall.

Commit bbc9651f

 ("drm/xe/irq: move irq_uninstall over to devm")
resolved the ordering issue where irq_uninstall (registered with drmm)
was called after pci_free_irq_vectors (registered with devm upon calling
pci_alloc_irq_vectors). This happened because drmm action list is
registered with devm very early in the init flow - before
pci_alloc_irq_vectors.

Now that irq_uninstall is registered with devm, it will be called before
pci_free_irq_vectors and we can remove xe_irq_shutdown.

Signed-off-by: Ilia Levi <illevi@habana.ai>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240606124705.822451-1-illevi@habana.ai
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>