IB/mthca: Distinguish multiple devices in /proc/interrupts

When the mthca driver uses the same name for interrupts for every
device in the system.  This can make it very confusing trying to work
out exactly which device MSI-X interrupts are for.  Change the driver
to add the PCI name of the device to the interrupt name.

Signed-off-by: Arputham Benjamin <abenjamin@sgi.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>