Merge commit 'fca3c3b61952aacc45e9ca54d86a762946c21942'

Merge commit 'fca3c3b61952aacc45e9ca54d86a762946c21942'

* commit 'fca3c3b61952aacc45e9ca54d86a762946c21942':
  hevc: Add AVX2 DC IDCT

Mostly noop as we already have that code.

In the ASM, code is merged with the exception of SECTION which is kept
uppercase for consistency with the rest of the codebase.

Still in the ASM, the prototype comment is fixed to honor the '_' added
from the original commit.

idct_dc_proto() is dropped as it's not used anymore here.

Merged-by: Clément Bœsch <cboesch@gopro.com>