Add the comment for function 'IsValidSplit' in 'Shell.c'. Add code to check whether pointer 'DataBuffer' in 'DmpStore.c' is NULL before used.

Signed-off-by: Shumin Qiu <shumin.qiu@intel.com>
Reviewed-by: Jaben Carsey <Jaben.carsey@intel.com>




git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15051 6f19259b-4bc3-4df7-8a09-765794883524