[PATCH] drm/i915/ringbuffer: change header SPDX identifier to MIT

[Chris Wilson]

Quoting Jonathan Gray (2018-10-31 00:53:31)
> Commit b24413180f5600bcb3bb70fbed5cf186b60864bd added
> "SPDX-License-Identifier: GPL-2.0" to files which previously had no
> license, change this to MIT for intel_ringbuffer.h matching the license
> text of intel_ringbuffer.c.
> 
> Signed-off-by: Jonathan Gray <jsg at jsg.id.au>
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris