Commit 5bab6f60cb4d ("drm/i915: Serialise updates to GGTT with access
through GGTT on Braswell") depended upon a working stop_machine() and
so forced the selection of STOP_MACHINE. However, commit 86fffe4a61dd
("kernel: remove stop_machine() Kconfig dependency") removed the option
STOP_MACHINE from init/Kconfig and ensured that stop_machine()
universally works. Due to the order in which the patches were applied,
removing the select from DRM_I915 got lost during merging.