Bluetooth: tests: Fix Makefiles comments

Those tests are now build with unified kernel.

Change-Id: Idbc42bb77060cea0130d62cccdf2e40aeee89128
Signed-off-by: Szymon Janc <ext.szymon.janc@tieto.com>

tests/bluetooth/shell/Makefile

-# Makefile - Bluetooth shell Makefile for microkernel
+# Makefile - Bluetooth shell
 
 #
 # Copyright (c) 2015-2016 Intel Corporation

tests/bluetooth/tester/Makefile

-# Makefile - Bluetooth tester Makefile for microkernel
+# Makefile - Bluetooth tester
 
 #
 # Copyright (c) 2015-2016 Intel Corporation