Apply fc7bf4c0d65a342b29fe38c332db3fe900b481b9 to 5.15

[Nathan Chancellor <nathan@kernel.org>]

Hi stable folks,

Please apply commit fc7bf4c0d65a ("drm/i915/selftests: Fix inconsistent
IS_ERR and PTR_ERR") to 5.15, where it resolves a couple of instances of
-Wuninitialized with clang-21 or newer that were introduced by commit
cdb35d1ed6d2 ("drm/i915/gem: Migrate to system at dma-buf attach time
(v7)") in 5.15.

  In file included from drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c:329:
  drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c:105:18: error: variable 'dmabuf' is uninitialized when used here [-Werror,-Wuninitialized]
    105 |                        PTR_ERR(dmabuf));
        |                                ^~~~~~
  drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c:94:24: note: initialize the variable 'dmabuf' to silence this warning
     94 |         struct dma_buf *dmabuf;
        |                               ^
        |                                = NULL
  drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c:161:18: error: variable 'dmabuf' is uninitialized when used here [-Werror,-Wuninitialized]
    161 |                        PTR_ERR(dmabuf));
        |                                ^~~~~~
  drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c:149:24: note: initialize the variable 'dmabuf' to silence this warning
    149 |         struct dma_buf *dmabuf;
        |                               ^
        |                                = NULL

It applies and builds cleanly for me. If there are any issues, please
let me know.

Cheers,
Nathan