[partition] Move encryption state-calculation to state()

Previously, state() just returned a stored state, which changed
via updateState(). However, when updateState() started taking
visibility-of-the-widget into account, it became possible to
de-sync the *apparent* state of the encryption widget, from the
stored one:
- make an encryption widget, which is not visible
- show it.

Now the stored-state takes visibility into account that is
different (hidden, so we end up with a state of Unconfirmed)
from the apparent value (shown and unchecked).

Move the calculation to state() instead, so whenever queried,
it checks the current checks-and-visibility values. Restore
the previously-reverted bit for accepting LUKS partitions.

SEE #1935
SEE #1953

src/modules/partition/gui/EncryptWidget.cpp

@@ -85,7 +85,26 @@ EncryptWidget::reset( bool checkVisible )
 EncryptWidget::Encryption
 EncryptWidget::state() const
 {
-    return m_state;
+    Encryption newState = Encryption::Unconfirmed;
+
+    if ( m_ui->m_encryptCheckBox->isChecked() || !m_ui->m_encryptCheckBox->isVisible() )
+    {
+        if ( !m_ui->m_passphraseLineEdit->text().isEmpty()
+             && m_ui->m_passphraseLineEdit->text() == m_ui->m_confirmLineEdit->text() )
+        {
+            newState = Encryption::Confirmed;
+        }
+        else
+        {
+            newState = Encryption::Unconfirmed;
+        }
+    }
+    else
+    {
+        newState = Encryption::Disabled;
+    }
+
+    return newState;
 }
 
 
@@ -148,23 +167,7 @@ EncryptWidget::updateState()
         }
     }
 
-    Encryption newState;
+    Encryption newState = state();
-    if ( m_ui->m_encryptCheckBox->isChecked() )
-    {
-        if ( !m_ui->m_passphraseLineEdit->text().isEmpty()
-             && m_ui->m_passphraseLineEdit->text() == m_ui->m_confirmLineEdit->text() )
-        {
-            newState = Encryption::Confirmed;
-        }
-        else
-        {
-            newState = Encryption::Unconfirmed;
-        }
-    }
-    else
-    {
-        newState = Encryption::Disabled;
-    }
 
     if ( newState != m_state )
     {