intel/isl: Fix isl_color_value_unpack to match the prototype
The prototype uses a pointer and the actual function definition had an array. For some reason, GCC never complained about this until GCC 11. This fixes a compile warning when building with GCC 11. Fixes: 09ced654 "intel/isl: Add format conversion code" Reviewed-by:Tapani Pälli <tapani.palli@intel.com> Part-of: <!10537>