Use right mnemonic_widget id

Change-Id: Ia5be89f17d8e63ad67a8d1dc811927dcdebbc0a9
diff --git a/sc/uiconfig/scalc/ui/formulacalculationoptions.ui b/sc/uiconfig/scalc/ui/formulacalculationoptions.ui
index bb0f02e..0a806b0 100644
--- a/sc/uiconfig/scalc/ui/formulacalculationoptions.ui
+++ b/sc/uiconfig/scalc/ui/formulacalculationoptions.ui
@@ -261,7 +261,7 @@
                                <property name="can_focus">False</property>
                                <property name="xalign">0</property>
                                <property name="label" translatable="yes">OpenCL Platform Vendor</property>
                                <property name="mnemonic_widget">openclvendor:border</property>
                                <property name="mnemonic_widget">platformvendor:border</property>
                              </object>
                              <packing>
                                <property name="left_attach">0</property>