PCI: dwc: Move MSI IRQs allocation to IRQ domains hierarchical API

Implement a multiplexed IRQ domain hierarchy API in the pcie-designware
host bridge driver that funnels all MSI IRQs into a single parent
interrupt, moving away from the obsolete struct msi_controller based
API.

Although the old implementation API is still available, pcie-designware
will now use the multiplexed IRQ domains hierarchical API.

Remove all existing dwc based host bridges MSI IRQs handlers, in that the
hierarchical API now handles MSI IRQs through the hierarchical/chained
MSI domain implementation.

Signed-off-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Tested-by: Niklas Cassel <niklas.cassel@axis.com>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Acked-by: Jingoo Han <jingoohan1@gmail.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>