gui: Fix disk config menu description

The saveMedias variable is responsible for selecting between loading the
page or resetting page state on cancel button clicks. When clicking the
confirm button, saveMedias must be set to nil to prevent flipping the
logic for loading the page and cancel button clicks. This logic
inversion led to incorrect menu descriptions for the disk config page.

Signed-off-by: John Akre <john.w.akre@intel.com>

gui/pages/disk_config.go

@@ -934,6 +934,7 @@ func (disk *DiskConfig) GetTitle() string {
 // StoreChanges will store this pages changes into the model
 func (disk *DiskConfig) StoreChanges() {
 	var installBlockDevice *storage.BlockDevice
+	disk.saveMedias = nil
 
 	if disk.safeButton.GetActive() {
 		disk.model.ClearInstallSelected()