drm/i915: Capture PCI revision and subsytem details in error state

Revision id along with device id is useful in better identification of the HW
and its limitations so include this detail in error state.

v2: make it clear that it is PCI revision and We might as well dump PCI
subsystem details while we update this (Ville, Chris).

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NArun Siluvery <arun.siluvery@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1454001521-7701-1-git-send-email-arun.siluvery@linux.intel.com

drivers/gpu/drm/i915/i915_gpu_error.c

@@ -365,6 +365,10 @@ int i915_error_state_to_str(struct drm_i915_error_state_buf *m,
 	err_printf(m, "Reset count: %u\n", error->reset_count);
 	err_printf(m, "Suspend count: %u\n", error->suspend_count);
 	err_printf(m, "PCI ID: 0x%04x\n", dev->pdev->device);
+	err_printf(m, "PCI Revision: 0x%02x\n", dev->pdev->revision);
+	err_printf(m, "PCI Subsystem: %04x:%04x\n",
+		   dev->pdev->subsystem_vendor,
+		   dev->pdev->subsystem_device);
 	err_printf(m, "IOMMU enabled?: %d\n", error->iommu);
 
 	if (HAS_CSR(dev)) {