drm/i915: move uapi.event outside spinlock in intel_crtc_vblank_work

drm/i915: move uapi.event outside spinlock in intel_crtc_vblank_work

In intel_crtc_vblank_work(), we access uapi.event before grabbing the
event_lock spinlock, but modify it inside the spinlock block.  This
causes some static analyzers to get confused and issue a warning.

The uapi.event value is not protected by the event_lock, so we can
safely move it out of the protected block to prevent false positives.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240528112901.476068-3-luciano.coelho@intel.com