drm: Use correct spinlock flavor in drm_vblank_get()

The irq flags state is already established by the outer
spin_lock_irqsave(); re-disabling irqs is redundant.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
1 file changed