ShellPkg: Fix the ASSERT issue in drvcfg command.

Initialize the local pointer to avoid to free a dangling pointer.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Qiu Shumin <shumin.qiu@intel.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18327 6f19259b-4bc3-4df7-8a09-765794883524

ShellPkg/Library/UefiShellDriver1CommandsLib/DrvCfg.c

@@ -1171,6 +1171,7 @@ ShellCommandRunDrvCfg (
   Status              = EFI_SUCCESS;
   Language            = NULL;
   UseHii              = TRUE;
+  ProblemParam        = NULL;
 
   //
   // initialize the shell lib (we must be in non-auto-init...)