HAL_Empty: make I2C ops fail

libraries/AP_HAL_Empty/I2CDriver.cpp

@@ -10,12 +10,12 @@ void EmptyI2CDriver::setTimeout(uint16_t ms) {}
 void EmptyI2CDriver::setHighSpeed(bool active) {}
 
 uint8_t EmptyI2CDriver::write(uint8_t addr, uint8_t len, uint8_t* data)
-{return 0;} 
+{return 1;} 
 uint8_t EmptyI2CDriver::writeRegister(uint8_t addr, uint8_t reg, uint8_t val)
-{return 0;}
+{return 1;}
 uint8_t EmptyI2CDriver::writeRegisters(uint8_t addr, uint8_t reg,
                                uint8_t len, uint8_t* data)
-{return 0;}
+{return 1;}
 
 uint8_t EmptyI2CDriver::read(uint8_t addr, uint8_t len, uint8_t* data)
 {
@@ -25,14 +25,14 @@ uint8_t EmptyI2CDriver::read(uint8_t addr, uint8_t len, uint8_t* data)
 uint8_t EmptyI2CDriver::readRegister(uint8_t addr, uint8_t reg, uint8_t* data)
 {
     *data = 0;
-    return 0;
+    return 1;
 }
 
 uint8_t EmptyI2CDriver::readRegisters(uint8_t addr, uint8_t reg,
                                       uint8_t len, uint8_t* data)
 {
     memset(data, 0, len);    
-    return 0;
+    return 1;
 }
 
 uint8_t EmptyI2CDriver::lockup_count() {return 0;}