Remove non-ascii char from comments.

Fixes KhronosGroup#4851

source/val/validate_image.cpp

@@ -1995,11 +1995,11 @@ spv_result_t ValidateImageQueryLod(ValidationState_t& _,
            << " components, but given only " << actual_coord_size;
   }
 
-  // The operad is a sampled image.
+  // The operand is a sampled image.
   // The sampled image type is already checked to be parameterized by an image
   // type with Sampled=0 or Sampled=1.  Vulkan bans Sampled=0, and so we have
   // Sampled=1.  So the validator already enforces Vulkan VUID 4659:
-  //   OpImageQuerySizeLod must only consume an “Image” operand whose type has
+  //   OpImageQuerySizeLod must only consume an "Image" operand whose type has
   //   its "Sampled" operand set to 1
   return SPV_SUCCESS;
 }