libcamera: v4l2_subdevice: Avoid unnecessary copy

There is no reason make a copy of the name, so don't do it,
and instead use a reference.

Signed-off-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Isaac Scott <isaac.scott@ideasonboard.com>

src/libcamera/v4l2_subdevice.cpp

@@ -1724,7 +1724,7 @@ const std::string &V4L2Subdevice::model()
 	 * part of the entity name before the first space if the name contains
 	 * an I2C address, and use the full entity name otherwise.
 	 */
-	std::string entityName = entity_->name();
+	const std::string &entityName = entity_->name();
 	static const std::regex i2cRegex{ " [0-9]+-[0-9a-f]{4}" };
 	std::smatch match;