drm/i915: Extract GT powermanagement interrupt handling

i915_irq.c is large. It serves as the central dispatch and handler for
all of our device interrupts. Pull out the GT pm interrupt handling
(leaving the central dispatch) so that we can encapsulate the logic a
little better.

Based on a patch by Chris Wilson.

Signed-off-by: Andi Shyti <andi.shyti@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190811142801.2460-1-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index a3f6f45..89f1a19 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -81,6 +81,7 @@
 	gt/intel_engine_user.o \
 	gt/intel_gt.o \
 	gt/intel_gt_pm.o \
+	gt/intel_gt_pm_irq.o \
 	gt/intel_hangcheck.o \
 	gt/intel_lrc.o \
 	gt/intel_renderstate.o \