ENABLE_AVX='ON' is deprecated

[gpkc]

OpenCV is giving a warning that this option is deprecated:

-- WARNING: Option ENABLE_AVX='ON' is deprecated and should not be used anymore
--          Behaviour of this option is not backward compatible
--          Refer to 'CPU_BASELINE'/'CPU_DISPATCH' CMake options documentation

[janza]

Removed that option in 4e0961e