BaseTools: Fixed a Incremental build issue

The .map file is not update to FFS_OUTPUT_DIR folder
in the incremental build.

Signed-off-by: Guo Dong <guo.dong@intel.com>
Signed-off-by: Bob Feng <bob.c.feng@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>