spirv: Add subgroup ballot support

Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>

src/compiler/spirv/spirv_to_nir.c

@@ -3296,6 +3296,11 @@ vtn_handle_preamble_instruction(struct vtn_builder *b, SpvOp opcode,
          spv_check_supported(subgroup_basic, cap);
          break;
 
+      case SpvCapabilitySubgroupBallotKHR:
+      case SpvCapabilityGroupNonUniformBallot:
+         spv_check_supported(subgroup_ballot, cap);
+         break;
+
       case SpvCapabilityVariablePointersStorageBuffer:
       case SpvCapabilityVariablePointers:
          spv_check_supported(variable_pointers, cap);