BaseTools: Update incorrect variable name 'DataPile'

BaseTools: Update incorrect variable name 'DataPile'

BZ:https://bugzilla.tianocore.org/show_bug.cgi?id=2093

The PlatformAutoGen object has a DataPipe property but no DataPile property
So change the variable name 'DataPile' to 'DataPipe' in BuildReport.py

This patch is going to fix that issue.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Bob Feng <bob.c.feng@intel.com>
Signed-off-by: Zhiju.Fan <zhijux.fan@intel.com>
Reviewed-by: Bob Feng <bob.c.feng@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>