Remove include <log.h> from defines.h

The reason for this is that log.h includes drv_hrt.h which sucks in
half the project's include files with it, which causes strange build
issues

platforms/common/px4_work_queue/WorkQueue.cpp

@@ -36,6 +36,7 @@
 
 #include <string.h>
 
+#include <px4_platform_common/log.h>
 #include <px4_platform_common/tasks.h>
 #include <px4_platform_common/time.h>
 #include <drivers/drv_hrt.h>