gstlal_play: simplify high/low pass filter if statements

gstlal/bin/gstlal_play

@@ -210,11 +210,10 @@ else:
 # handle filtering
 if options.high_pass_filter is not None and options.low_pass_filter is not None:
 	head = pipeparts.mkaudiochebband(pipeline, head, lower_frequency = options.high_pass_filter, upper_frequency = options.low_pass_filter)
-else:
-	if options.high_pass_filter is not None:
-		head = pipeparts.mkaudiocheblimit(pipeline, head, cutoff = options.high_pass_filter, mode = "high-pass")
-	elif options.low_pass_filter is not None:
-		head = pipeparts.mkaudiocheblimit(pipeline, head, cutoff = options.low_pass_filter, mode = "low-pass")
+elif options.high_pass_filter is not None:
+	head = pipeparts.mkaudiocheblimit(pipeline, head, cutoff = options.high_pass_filter, mode = "high-pass")
+elif options.low_pass_filter is not None:
+	head = pipeparts.mkaudiocheblimit(pipeline, head, cutoff = options.low_pass_filter, mode = "low-pass")
 
 # necessary audio convert and amplify 
 head = pipeparts.mkaudioconvert(pipeline, pipeparts.mkaudioamplify(pipeline, head, options.amplification))