MdeModulePkg/BMMUiLib: Fix incorrect variable name

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=592

In function UpdateConsoleContent, we compare console name
with "ErrOut" string to check whether the content in console
Error device page has been changed. But when call function
UpdateConsoleContent, we pass console name as "ConErr" by mistake.
This patch is to fix the inconsistent issue.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Dandan Bi <dandan.bi@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
(cherry picked from commit 983f599)

MdeModulePkg/Library/BootMaintenanceManagerUiLib/BootMaintenance.c

@@ -1302,7 +1302,7 @@ BootMaintCallback (
     } else if ((QuestionId >= CON_OUT_DEVICE_QUESTION_ID) && (QuestionId < CON_OUT_DEVICE_QUESTION_ID + MAX_MENU_NUMBER)) {
       UpdateConsoleContent (L"ConOut", CurrentFakeNVMap);
     } else if ((QuestionId >= CON_ERR_DEVICE_QUESTION_ID) && (QuestionId < CON_ERR_DEVICE_QUESTION_ID + MAX_MENU_NUMBER)) {
-      UpdateConsoleContent (L"ConErr", CurrentFakeNVMap);
+      UpdateConsoleContent (L"ErrOut", CurrentFakeNVMap);
     }
   }