drm/vblank: Use spin_(un)lock_irq() in drm_crtc_queue_sequence_ioctl()

This is an ioctl callback, so we're guaranteed to have IRQs enabled when
calling this function. Use the plain _irq() variants of spin_(un)lock()
to make this more obvious.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20200720190736.180297-6-lyude@redhat.com


Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>