intel_th: pci: Use MSI interrupt signalling

Since Intel TH is capable of MSI interrupt signalling, make use of it.
The way it works is, each of the 7 interrupt triggering events has its
own vector in this mode, as opposed to interrupt line delivery, where
all events are signalled via the same line. Failing to enable MSI, the
driver falls back to using an interrupt line.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hwtracing/intel_th/intel_th.h

@@ -238,6 +238,9 @@ enum th_mmio_idx {
 #define TH_CONFIGURABLE_MASTERS 256
 #define TH_MSC_MAX		2
 
+/* Maximum IRQ vectors */
+#define TH_NVEC_MAX		8
+
 /**
  * struct intel_th - Intel TH controller
  * @dev:	driver core's device