setup_board: Update usages

BUG=chromium:893748
TEST=precq
CQ-DEPEND=CL:1409763

Change-Id: I661c527c4a53864595d02f3302dbc9047692a042
Reviewed-on: https://chromium-review.googlesource.com/1407709
Commit-Ready: Alex Klein <saklein@chromium.org>
Tested-by: Alex Klein <saklein@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
diff --git a/build_tc.py b/build_tc.py
index 4f022d2..c14b690 100755
--- a/build_tc.py
+++ b/build_tc.py
@@ -59,8 +59,7 @@
     cross_symlink = os.path.join(self._chromeos_root, 'chroot',
                                  'usr/local/bin/emerge-%s' % self._board)
     if not os.path.exists(cross_symlink):
-      command = ('%s/setup_board --board=%s' % (misc.CHROMEOS_SCRIPTS_DIR,
-                                                self._board))
+      command = 'setup_board --board=%s' % self._board
       self._ce.ChrootRunCommand(self._chromeos_root, command)
 
   def Build(self):