Fixes #1530 cross ref to #1596

Added new code tested over win10 with screen custom to 100%
and screen custom to 125%
Having Single Disk chart loaded dynamically on widget resize
we have to compute offset width and height

Signed-off-by: Mirko Arena <mirko.arena@gmail.com>

src/rockstor/storageadmin/static/storageadmin/js/views/dashboard/disk_utilization.js

@@ -533,6 +533,10 @@ DiskUtilizationWidget = RockStorWidgetView.extend({
                 _this.selectedDisk = _this.$('#disk-select').val();
             });
             this.$('#top-disks-container').css('width', '60%');
+            this.$('#single-disk-chart').css('width', '100%');
+            this.$('#single-disk-chart').css('height', '100%');
+            this.$('#single-disk-chart').width =  this.$('#single-disk-chart').offsetWidth;
+            this.$('#single-disk-chart').height =  this.$('#single-disk-chart').offsetHeight;
         } else {
             this.$('#top-disks-container').css('width', '70%');
             _this.SingleDiskgraphRendered = false;