drm/i915: Move GEM client throttling to its own file

Continuing the decluttering of i915_gem.c by moving the client self
throttling into its own file.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190528092956.14910-13-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index e1ed526..83588e9 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -104,6 +104,7 @@
 	gem/i915_gem_shmem.o \
 	gem/i915_gem_shrinker.o \
 	gem/i915_gem_stolen.o \
+	gem/i915_gem_throttle.o \
 	gem/i915_gem_tiling.o \
 	gem/i915_gem_userptr.o \
 	gem/i915_gem_wait.o \