drm/i915: Move GEM object waiting to its own file

Continuing the decluttering of i915_gem.c by moving the object wait
decomposition 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/20190528092956.14910-11-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 44d6e0b..a4ea6f6 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -105,6 +105,7 @@
 	gem/i915_gem_stolen.o \
 	gem/i915_gem_tiling.o \
 	gem/i915_gem_userptr.o \
+	gem/i915_gem_wait.o \
 	gem/i915_gemfs.o
 i915-y += \
 	  $(gem-y) \