Documentation/gpu: Disambiguate SPI term

Documentation/userspace-api/media/glossary.rst:170: WARNING: duplicate term description of SPI, other instance in gpu/amdgpu/amdgpu-glossary

That's because SPI of amdgpu (Shader Processor Input) shares the same
global glossary term as SPI of media subsystem (which is Serial
Peripheral Interface Bus). Disambiguate the former from the latter to
fix the warning.

Note that adding context qualifiers in the term is strictly necessary
in order to make Sphinx happy.

Fixes: dd3d035a ("Documentation/gpu: Add new entries to amdgpu glossary")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Closes: https://lore.kernel.org/linux-next/20250509185845.60bf5e7b@canb.auug.org.au/


Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>