[Coverage] Delete useless brackets

BZ: 115218

Some brackets around return value were used to wrap lines that did not
need to be wrapped.

Unwrap lines and delete the brackets.

Change-Id: I7583deff42b8b4db1ef7dbb61f24329dec908ec3
Signed-off-by: Kevin Rocard <kevinx.rocard@intel.com>
Reviewed-on: http://android.intel.com:8080/112708
Reviewed-by: Denneulin, Guillaume <guillaume.denneulin@intel.com>
Reviewed-by: Gonzalve, Sebastien <sebastien.gonzalve@intel.com>
Reviewed-by: cactus <cactus@intel.com>
Tested-by: Dixon, CharlesX <charlesx.dixon@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>
diff --git a/tools/coverage.py b/tools/coverage.py
index e017cf5..c4250fa 100755
--- a/tools/coverage.py
+++ b/tools/coverage.py
@@ -50,13 +50,11 @@
 
 class ChildNotFoundError(ChildError):
 	def __str__(self):
-		return ("Unable to find the child %s in %s" %
-				(self.child, self.parent))
+		return "Unable to find the child %s in %s" % (self.child, self.parent)
 
 class DuplicatedChildError(ChildError):
 	def __str__(self):
-		return ("Add existing child %s in %s. Did you restart de PFW ?" %
-				(self.child, self.parent))
+		return "Add existing child %s in %s." % (self.child, self.parent)
 
 class Element():
 	"""Root class for all coverage elements"""