Fix warning -Wimplicit-fallthrough

src/drivers/lis3mdl/lis3mdl_i2c.cpp

@@ -114,6 +114,8 @@ LIS3MDL_I2C::ioctl(unsigned operation, unsigned &arg)
 	case MAGIOCGEXTERNAL:
 		external();
 
+	/* FALLTHROUGH */
+
 	case DEVIOCGDEVICEID:
 		return CDev::ioctl(nullptr, operation, arg);
 

src/drivers/mpu6000/mpu6000_spi.cpp

@@ -242,6 +242,8 @@ MPU6000_SPI::ioctl(unsigned operation, unsigned &arg)
 	case ACCELIOCGEXTERNAL:
 		external();
 
+	/* FALLTHROUGH */
+
 	case DEVIOCGDEVICEID:
 		return CDev::ioctl(nullptr, operation, arg);
 

src/drivers/mpu9250/mpu9250_spi.cpp

@@ -170,6 +170,8 @@ MPU9250_SPI::ioctl(unsigned operation, unsigned &arg)
 	case ACCELIOCGEXTERNAL:
 		external();
 
+	/* FALLTHROUGH */
+
 	case DEVIOCGDEVICEID:
 		return CDev::ioctl(nullptr, operation, arg);
 

src/drivers/protocol_splitter/protocol_splitter.cpp

@@ -379,7 +379,8 @@ ssize_t Mavlink2Dev::write(struct file *filp, const char *buffer, size_t buflen)
 			return 0;
 		}
 
-	//no break
+	/* FALLTHROUGH */
+
 	case ParserState::GotLength: {
 			_packet_len -= buflen;
 			int buf_free;
@@ -509,8 +510,8 @@ ssize_t RtpsDev::write(struct file *filp, const char *buffer, size_t buflen)
 		_parser_state = ParserState::GotLength;
 		lock(Write);
 
+	/* FALLTHROUGH */
 
-	//no break
 	case ParserState::GotLength: {
 			_packet_len -= buflen;
 			int buf_free;