MdeModulePkg/NvmExpress: Fix mem leak in error handling of Start()

MdeModulePkg/NvmExpress: Fix mem leak in error handling of Start()

Memory pointed to by Private->ControllerData has not been freed up
correctly at error handling path.

Cc: Simon (Xiang) Lian-SSI <simon.lian@ssi.samsung.com>
Cc: Star Zeng <star.zeng@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Feng Tian <feng.tian@intel.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Simon (Xiang) Lian-SSI <simon.lian@ssi.samsung.com>