bugfix: NMEA GPS update rate was 0 since num_bytes_read was not being… (#23957)

* bugfix: NMEA GPS update rate was 0 since num_bytes_read was not being updated

* Update gps.cpp

style fix

* make format

---------

Co-authored-by: Jacob Dahl <[email protected]>

Author: dronesalot

src/drivers/gps/gps.cpp

@@ -476,6 +476,10 @@ int GPS::pollOrRead(uint8_t *buf, size_t buf_length, int timeout)
 	if (_interface == GPSHelper::Interface::UART) {
 		ret = _uart.readAtLeast(buf, buf_length, math::min(character_count, buf_length), timeout_adjusted);
 
+		if (ret > 0) {
+			_num_bytes_read += ret;
+		}
+
 // SPI is only supported on LInux
 #if defined(__PX4_LINUX)