drm/i915: Fix doclinks

Update locations for

./drivers/gpu/drm/i915/i915_vma.h:1: warning: 'Virtual Memory Address' not found
./drivers/gpu/drm/i915/i915_gem_gtt.c:1: warning: 'Global GTT views' not found

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200302145254.520447-1-chris@chris-wilson.co.uk

Documentation/gpu/i915.rst

@@ -332,7 +332,7 @@ This process is dubbed relocation.
 GEM BO Management Implementation Details
 ----------------------------------------
 
-.. kernel-doc:: drivers/gpu/drm/i915/i915_vma.h
+.. kernel-doc:: drivers/gpu/drm/i915/i915_vma_types.h
    :doc: Virtual Memory Address
 
 Buffer Object Eviction
@@ -382,7 +382,7 @@ Logical Rings, Logical Ring Contexts and Execlists
 Global GTT views
 ----------------
 
-.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_gtt.c
+.. kernel-doc:: drivers/gpu/drm/i915/i915_vma_types.h
    :doc: Global GTT views
 
 .. kernel-doc:: drivers/gpu/drm/i915/i915_gem_gtt.c