Bugfix: make sure device is not open when attempting to closing it

plugins/samplesource/bladerfinput/bladerfinput.cpp

@@ -146,6 +146,10 @@ void BladerfInput::closeDevice()
 {
     int res;
 
+    if (m_dev == 0) { // was never open
+        return;
+    }
+
     if ((res = bladerf_enable_module(m_dev, BLADERF_MODULE_RX, false)) < 0)
     {
         qCritical("BladerfInput::stop: bladerf_enable_module with return code %d", res);

plugins/samplesource/fcdpro/fcdproinput.cpp

@@ -117,6 +117,10 @@ bool FCDProInput::start()
 
 void FCDProInput::closeDevice()
 {
+    if (m_dev == 0) { // was never open
+        return;
+    }
+
     fcdClose(m_dev);
     m_dev = 0;
 }

plugins/samplesource/fcdproplus/fcdproplusinput.cpp

@@ -111,6 +111,10 @@ bool FCDProPlusInput::start()
 
 void FCDProPlusInput::closeDevice()
 {
+    if (m_dev == 0) { // was never open
+        return;
+    }
+
     fcdClose(m_dev);
     m_dev = 0;
 }

plugins/samplesource/limesdrinput/limesdrinput.cpp

@@ -133,6 +133,10 @@ bool LimeSDRInput::openDevice()
 
 void LimeSDRInput::closeDevice()
 {
+    if (m_deviceShared.m_deviceParams->getDevice() == 0) { // was never open
+        return;
+    }
+
     // release the channel
 
     if (LMS_EnableChannel(m_deviceShared.m_deviceParams->getDevice(), LMS_CH_RX, m_deviceShared.m_channel, false) != 0)