Wire: allow scanning bus via beginTransmission-endTransmission

libraries/Wire/Wire.cpp

@@ -109,12 +109,6 @@ uint8_t TwoWire::endTransmission(bool stopBit)
 {
   transmissionBegun = false ;
 
-  // Check if there are data to send
-  if ( txBuffer.available() == 0)
-  {
-    return 4 ;
-  }
-
   // Start I2C transmission
   if ( !sercom->startTransmissionWIRE( txAddress, WIRE_WRITE_FLAG ) )
   {