drm/i915: Organize PDP regs report for future.

Let's be optimistic that for future platforms this will remain the same
and reorg a bit.
This reorg in if blocks instead of switch make life easier for future
platform support addition.

Cc: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gpu_error.c

@@ -912,26 +912,20 @@ static void i915_record_ring_state(struct drm_device *dev,
 
 		ering->vm_info.gfx_mode = I915_READ(RING_MODE_GEN7(ring));
 
-		switch (INTEL_INFO(dev)->gen) {
-		case 9:
-		case 8:
+		if (IS_GEN6(dev))
+			ering->vm_info.pp_dir_base =
+				I915_READ(RING_PP_DIR_BASE_READ(ring));
+		else if (IS_GEN7(dev))
+			ering->vm_info.pp_dir_base =
+				I915_READ(RING_PP_DIR_BASE(ring));
+		else if (INTEL_INFO(dev)->gen >= 8)
 			for (i = 0; i < 4; i++) {
 				ering->vm_info.pdp[i] =
 					I915_READ(GEN8_RING_PDP_UDW(ring, i));
 				ering->vm_info.pdp[i] <<= 32;
 				ering->vm_info.pdp[i] |=
 					I915_READ(GEN8_RING_PDP_LDW(ring, i));
 			}
-			break;
-		case 7:
-			ering->vm_info.pp_dir_base =
-				I915_READ(RING_PP_DIR_BASE(ring));
-			break;
-		case 6:
-			ering->vm_info.pp_dir_base =
-				I915_READ(RING_PP_DIR_BASE_READ(ring));
-			break;
-		}
 	}
 }