BaseTools: Sort the Pcd set when generating the VPD binary

If VPD PcdNvStoreDefaultValueBuffer is used, all DynamicHii and
DynamicExHii PCD value will be generated into that VPD.

In order to generate the same VPD binary file in every build,
sort the Pcd set when generating VPD.

Signed-off-by: Bob Feng <bob.c.feng@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Yuwei Chen <yuwei.chen@intel.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>
Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>