misc: pci_endpoint_test: Add support to not enable MSI interrupts

misc: pci_endpoint_test: Add support to not enable MSI interrupts

Some platforms like TI's K2G have a restriction that the host side buffer
address should be aligned to either 1MB/2MB/4MB or 8MB addresses depending
on how it is configured in the endpoint (Ref: 11.14.4.9.1 Outbound Address
Translation in K2G TRM SPRUHY8F January 2016 – Revised May 2017). This
restriction also applies to the MSI addresses provided by the RC. However
it's not possible for the RC to know about this restriction and it may not
provide 1MB/2MB/4MB or 8MB aligned address. So MSI interrupts should be
disabled even if the K2G EP has MSI capabiltiy register.

Add support to not enable MSI interrupts in pci_endpoint_test driver so
that it can be used to test K2G EP.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>