videosettingspage: remove useless label

if no video device is detected "Preview unavailable" is just useless
as there is no video device listed.

Change-Id: I071da1e211b16f807ed22f69186a567db054c373
GitLab: #1076

src/app/settingsview/components/VideoSettingsPage.qml

@@ -249,21 +249,6 @@ SettingsPageBase {
                     generalSettings.startPreviewing(true);
                 }
             }
-
-            Text {
-                visible: VideoDevices.listSize === 0
-
-                Layout.fillWidth: true
-                Layout.preferredHeight: JamiTheme.preferredFieldHeight
-
-                text: JamiStrings.previewUnavailable
-                font.pointSize: JamiTheme.settingsFontSize
-                font.kerning: true
-                color: JamiTheme.primaryForegroundColor
-
-                horizontalAlignment: Text.AlignHCenter
-                verticalAlignment: Text.AlignVCenter
-            }
         }
     }
 }