cmake remove circular linking and reorganize

- px4_add_module now requires MAIN
 - px4_add_library doesn't automatically link

src/drivers/linux_pwm_out/CMakeLists.txt

@@ -40,6 +40,5 @@ px4_add_module(
 		linux_pwm_out.cpp
 		ocpoc_mmap.cpp
 	DEPENDS
-		platforms__common
 	)
-# vim: set noet ft=cmake fenc=utf-8 ff=unix :
+

src/drivers/linux_pwm_out/linux_pwm_out.cpp

@@ -50,7 +50,7 @@
 #include <drivers/drv_mixer.h>
 #include <lib/mixer/mixer.h>
 #include <lib/mixer/mixer_load.h>
-#include <systemlib/param/param.h>
+#include <parameters/param.h>
 #include <systemlib/pwm_limit/pwm_limit.h>
 
 #include "common.h"