PCI: keystone: Convert to using hierarchy domain for legacy interrupts

commit 6aed116cd98bebc49ae9b7b6df299ca7a4da91f8 from
git://git.ti.com/ti-linux-kernel/ti-linux-kernel.git



K2G provides separate IRQ lines for each of the four legacy interrupts.
Model this using hierarchy domain instead of linear domain with chained
IRQ handler.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Achal Verma <a-verma1@ti.com>
Link: https://lore.kernel.org/linux-pci/20210325090026.8843-5-kishon@ti.com/


Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Xulin Sun <xulin.sun@windriver.com>