fix(httpc): Fix data read was less than expected (#10019)

Author: Jason2866

Diff for: libraries/HTTPClient/src/HTTPClient.cpp

@@ -1423,7 +1423,7 @@ int HTTPClient::writeToStreamDataBlock(Stream * stream, int size)
                     // some time for the stream
                     delay(1);
 
-                    int leftBytes = (readBytes - bytesWrite);
+                    int leftBytes = (bytesRead - bytesWrite);
 
                     // retry to send the missed bytes
                     bytesWrite = stream->write((buff + bytesWrite), leftBytes);
@@ -1446,7 +1446,7 @@ int HTTPClient::writeToStreamDataBlock(Stream * stream, int size)
 
                 // count bytes to read left
                 if(len > 0) {
-                    len -= readBytes;
+                    len -= bytesRead;
                 }
 
                 delay(0);