-Wunintialized was disabled in commit c5627461490e ("drm/i915: Disable
-Wuninitialized") because there were two warnings that were false
positives. The first was due to DECLARE_WAIT_QUEUE_HEAD_ONSTACK, which
was fixed in LLVM 9.0.0. The second was in busywait_stop, which was
fixed in LLVM 10.0.0 (issue 415). The kernel's minimum version for LLVM
is 10.0.1 so this warning can be safely enabled, where it has already
caught a couple bugs.