Platform/Intel/Vlv2TbltDevicePkg: Add NetworkPkg.dec as the package dependency

NetLib will be moved from MdeModulePkg and NetworkPkg.
So, the module that consumes NetLib need to depend on NetworkPkg.dec.

Signed-off-by: Liming Gao <liming.gao@intel.com>
Cc: Zailiang Sun <zailiang.sun@intel.com>
Cc: Yi Qian <yi.qian@intel.com>
Reviewed-by: Zailiang Sun <zailiang.sun@intel.com>