[welcome] Simplify logic

- \not mandatorySatisfied \implies \not requirementsSatisfied,
   so the ifs can be combined and simplified

src/modules/welcome/checker/ResultsListWidget.cpp

@@ -215,9 +215,9 @@ ResultsListWidget::ResultsListWidget( QWidget* parent, const Calamares::Requirem
                                              "might be disabled." );
                                    m_explanation->setText( message.arg( *Calamares::Branding::ShortVersionedName ) ); )
         }
+        mainLayout->addStretch();
     }
-
+    else
-    if ( requirementsSatisfied && mandatorySatisfied )
     {
         if ( !Calamares::Branding::instance()->imagePath( Calamares::Branding::ProductWelcome ).isEmpty() )
         {
@@ -249,10 +249,6 @@ ResultsListWidget::ResultsListWidget( QWidget* parent, const Calamares::Requirem
                                                            .arg( *Calamares::Branding::ProductName ) );
                                m_explanation->setAlignment( Qt::AlignCenter ); )
     }
-    else
-    {
-        mainLayout->addStretch();
-    }
 
     CALAMARES_RETRANSLATE_SLOT( &ResultsListWidget::retranslate )
     retranslate();