lspci: Print PCIe Interrupt Message Numbers consistently

lspci: Print PCIe Interrupt Message Numbers consistently

Several Capabilities include MSI/MSI-X Interrupt Message Numbers, which
were decoded in various ways:

  - MSI %02x                             PCIe Capability
  - IntMsg %d                            AER Capability
  - INT Msg #%d                          DPC Capability
  - Interrupt Message Number %03x        SR-IOV Capability
  - Interrupt Message Number %03x        DOE Capability

Print them all using the same format:

  + IntMsgNum %d

This better matches the "Interrupt Message Number" terminology used in the
spec, e.g., PCIe r6.0, sec 7.5.3.2.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>