EKF: Correct units in comments

EKF/common.h

@@ -311,7 +311,7 @@ struct parameters {
 						///< the EKF will report that it is dead-reckoning (uSec)
 
 	// multi-rotor drag specific force fusion
-	float drag_noise{2.5f};			///< observation noise for drag specific force measurements (m/sec**2)
+	float drag_noise{2.5f};			///< observation noise variance for drag specific force measurements (m/sec**2)**2
 	float bcoef_x{25.0f};			///< ballistic coefficient along the X-axis (kg/m**2)
 	float bcoef_y{25.0f};			///< ballistic coefficient along the Y-axis (kg/m**2)
 

EKF/drag_fusion.cpp

@@ -48,7 +48,7 @@ void Ekf::fuseDrag()
 	float H_ACC[24] = {}; // Observation Jacobian
 	float SK_ACC[9] = {}; // Variable used to optimise calculations of the Kalman gain vector
 	float Kfusion[24] = {}; // Kalman gain vector
-	float R_ACC = _params.drag_noise; // observation noise in specific force drag (m/sec**2)
+	float R_ACC = _params.drag_noise; // observation noise variance in specific force drag (m/sec**2)**2
 
 	float rho = fmaxf(_air_density, 0.1f); // air density (kg/m**3)