AC_PosControl: fix typo in D-filter definition

libraries/AC_AttitudeControl/AC_PosControl.cpp

@@ -80,7 +80,7 @@ void AC_PosControl::set_dt(float delta_sec)
     _dt = delta_sec;
 
     // update rate controller's d filter
-    _pid_alt_accel.set_d_lpf_alpha(POSCONTROOL_ACCEL_Z_DTERM_FILTER, _dt);
+    _pid_alt_accel.set_d_lpf_alpha(POSCONTROL_ACCEL_Z_DTERM_FILTER, _dt);
 }
 
 /// set_speed_z - sets maximum climb and descent rates

libraries/AC_AttitudeControl/AC_PosControl.h

@@ -36,7 +36,7 @@
 
 #define POSCONTROL_ACTIVE_TIMEOUT_MS            200     // position controller is considered active if it has been called within the past 200ms (0.2 seconds)
 
-#define POSCONTROOL_ACCEL_Z_DTERM_FILTER        20      // Z axis accel controller's D term filter (in hz)
+#define POSCONTROL_ACCEL_Z_DTERM_FILTER         20      // Z axis accel controller's D term filter (in hz)
 
 class AC_PosControl
 {