MinPlatformPkg/Include: Add PEI DevicePathLib instance

PEI DevicePathLib instance required by NvmExpressPei.inf
due to recent change.

Cc: Chasel Chiu <chasel.chiu@intel.com>
Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Eric Dong <eric.dong@intel.com>
Signed-off-by: Isaac Oram <isaac.w.oram@intel.com>
Reviewed-by: Sai Chaganty <rangasai.v.chaganty@intel.com>