This MSI driver can be used on 83xx/85xx/86xx board.
In this driver, virtual interrupt host and chip were
setup. There are 256 MSI interrupts in this host, Every 32
MSI interrupts cascaded to one IPIC/MPIC interrupt.
The chip was treated as edge sensitive and some necessary
functions were setup for this chip.

Before using the MSI interrupt, PCI/PCIE device need to
ask for a MSI interrupt in the 256 MSI interrupts. A 256bit
bitmap show which MSI interrupt was used, reserve bit in
the bitmap can be used to force the device use some designate
MSI interrupt in the 256 MSI interrupts. Sometimes this is useful
for testing the all the MSI interrupts. The msi-available-ranges
property in the dts file was used for this purpose.

Signed-off-by: Jason Jin <Jason.jin@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>