AP_LANDING_GEAR: Remove deploy lock

Since the RC switches only respond to changes, there is no longer a need
for this lock state. The gear can be retracted or deployed by RC switch,
flight mode, or mavlink command freely without convoluted unlocking
methods.  Also removed use of this in the associated Copter code.

ArduCopter/landing_gear.cpp

@@ -15,7 +15,7 @@ void Copter::landinggear_update()
     // if we are doing an automatic landing procedure, force the landing gear to deploy.
     // To-Do: should we pause the auto-land procedure to give time for gear to come down?
     if (flightmode->landing_gear_should_be_deployed()) {
-        landinggear.set_position(AP_LandingGear::LandingGear_Deploy_And_Keep_Deployed);
+        landinggear.set_position(AP_LandingGear::LandingGear_Deploy);
     }
 
     // send event message to datalog if status has changed

libraries/AP_LandingGear/AP_LandingGear.cpp

@@ -58,17 +58,10 @@ void AP_LandingGear::set_position(LandingGearCommand cmd)
 {
     switch (cmd) {
         case LandingGear_Retract:
-            if (!_deploy_lock) {
             retract();
-            }
             break;
         case LandingGear_Deploy:
             deploy();
-            _deploy_lock = false;
-            break;
-        case LandingGear_Deploy_And_Keep_Deployed:
-            deploy();
-            _deploy_lock = true;
             break;
     }
 }

libraries/AP_LandingGear/AP_LandingGear.h

@@ -25,7 +25,6 @@ public:
     enum LandingGearCommand {
         LandingGear_Retract,
         LandingGear_Deploy,
-        LandingGear_Deploy_And_Keep_Deployed,
     };
 
     // Gear command modes
@@ -54,7 +53,6 @@ private:
 
     // internal variables
     bool        _deployed;              // true if the landing gear has been deployed, initialized false
-    bool        _deploy_lock;           // used to force landing gear to remain deployed until another regular Deploy command is received to reduce accidental retraction
     
     /// retract - retract landing gear
     void retract();