MdePkg/UefiDevicePathLib: Add a checking step

MdePkg/UefiDevicePathLib: Add a checking step

Add a checking step in DevicePathUtilities.c to verify DevicePath.
https://bugzilla.tianocore.org/show_bug.cgi?id=1372

v2: Remove ASSERT() and the redundant checking step. Update related
    description.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Shenglei Zhang <shenglei.zhang@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>