Add more check for the bmp file to avoid access violation.

Signed-off-by: Dong Eric <eric.dong@intel.com>
Reviewed-by: Gao Liming <liming.gao@intel.com>
Reviewed-by: Zhang Chao <chao.b.zhang@intel.com>

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@13185 6f19259b-4bc3-4df7-8a09-765794883524