Revert "Make pressing Enter a shortcut for the View action, in addition to V"

Turns out there is no good way to have a global shortcut with Enter that
does not interfere with the use of the enter key in child widgets.
This reverts commit 9ce6c24e1f.

manual/gui.rst

@@ -686,7 +686,7 @@ calibre has several keyboard shortcuts to save you time and mouse movement. Thes
       - Save to disk
     * - :kbd:`T`
       - Edit book
-    * - :kbd:`V` or `Enter`
+    * - :kbd:`V`
       - View
     * - :kbd:`Alt+V/Cmd+V in macOS`
       - View specific format

src/calibre/gui2/actions/view.py

@@ -36,7 +36,7 @@ def _triggered(self):
 class ViewAction(InterfaceAction):
 
     name = 'View'
-    action_spec = (_('View'), 'view.png', _('Read books'), (_('V'), 'Return'))
+    action_spec = (_('View'), 'view.png', _('Read books'), _('V'))
     action_type = 'current'
     action_add_menu = True
     action_menu_clone_qaction = True