Move the IRQ and MSI Domain configuration code to new helpers. No
functional changes.

Link: https://lore.kernel.org/r/20200728194945.14126-4-jonathan.derrick@intel.comSigned-off-by: NJon Derrick <jonathan.derrick@intel.com>
Signed-off-by: NLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@intel.com>