drm/i915: Split GEM object type definition to its own header

For convenience in avoiding inline spaghetti, keep the type definition
as a separate header.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190528092956.14910-1-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 139a0fc..23a45d7 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -85,6 +85,7 @@
 i915-y += $(gt-y)
 
 # GEM (Graphics Execution Management) code
+obj-y += gem/
 i915-y += \
 	  i915_active.o \
 	  i915_cmd_parser.o \