[PATCH 6/8] docs/gpu: fix a documentation build break in i915.rst

[Jonathan Corbet <corbet@xxxxxxx>]

Documentation/gpu/i915.rst is not included in the TOC tree, but newer
versions of sphinx parse it anyway.  That leads to this hard build failure:

> Global GTT Fence Handling
> ~~~~~~~~~~~~~~~~~~~~~~~~~
>
> reST markup error:
> /stuff/k/git/kernel/Documentation/gpu/i915.rst:403: (SEVERE/4) Title level inconsistent:

Make the underlining consistent and restore a working docs build.

Signed-off-by: Jonathan Corbet <corbet@xxxxxxx>
---
 Documentation/gpu/i915.rst | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/gpu/i915.rst b/Documentation/gpu/i915.rst
index 055df45596c1..cf9ff64753cc 100644
--- a/Documentation/gpu/i915.rst
+++ b/Documentation/gpu/i915.rst
@@ -401,13 +401,13 @@ GTT Fences and Swizzling
    :internal:
 
 Global GTT Fence Handling
-~~~~~~~~~~~~~~~~~~~~~~~~~
+-------------------------
 
 .. kernel-doc:: drivers/gpu/drm/i915/i915_gem_fence_reg.c
    :doc: fence register handling
 
 Hardware Tiling and Swizzling Details
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+-------------------------------------
 
 .. kernel-doc:: drivers/gpu/drm/i915/i915_gem_fence_reg.c
    :doc: tiling swizzling details
-- 
2.21.0