Fix page margins in preferences and cloudcredentials

- page margins are gridUnit / 2, consistent with other pages
- Simplify layout: we don't need to nest that much here, saves two
  objects and simplifies code a bit

Signed-off-by: Sebastian Kügler <sebas@kde.org>

qt-mobile/qml/CloudCredentials.qml

@@ -16,8 +16,11 @@ Item {
 	property bool issave: savePassword.checked;
 
 	ColumnLayout {
-		anchors.fill: parent
-		anchors.margins: MobileComponents.Units.gridUnit
+
+		anchors {
+			fill: parent
+			margins: MobileComponents.Units.gridUnit / 2
+		}
 
 		MobileComponents.Heading {
 			text: "Cloud credentials"

qt-mobile/qml/Preferences.qml

@@ -6,15 +6,17 @@ import QtQuick.Layouts 1.1
 import org.kde.plasma.mobilecomponents 0.2 as MobileComponents
 import org.subsurfacedivelog.mobile 1.0
 
-Item {
-	id: preferencesWindow
+
+GridLayout {
 
 	signal accept
 
-	GridLayout {
 	columns: 2
-		anchors.fill: parent
-		anchors.margins: MobileComponents.Units.gridUnit
+	width: parent.width - MobileComponents.Units.gridUnit
+	anchors {
+		fill: parent
+		margins: MobileComponents.Units.gridUnit / 2
+	}
 
 	MobileComponents.Heading {
 		text: "Preferences"
@@ -73,4 +75,3 @@ Item {
 		Layout.fillHeight: true
 	}
 }
-}