Misspell warnings fix (#2001)

erasure-utils.go

@@ -152,7 +152,7 @@ func getEncodedBlockLen(inputLen int64, dataBlocks int) (curEncBlockSize int64)
 // err == nil, not err == EOF. Additionally offset can be provided to start
 // the read at. copyN returns io.EOF if there aren't enough data to be read.
 func copyN(writer io.Writer, disk StorageAPI, volume string, path string, offset int64, length int64) (err error) {
-	// Use 128KiB staging buffer to read upto length.
+	// Use 128KiB staging buffer to read up to length.
 	buf := make([]byte, readSizeV1)
 
 	// Read into writer until length.