target: less implicit inclusion of "etm.h"

Don't include it in more headers than necessary; just
use it in the few files that actually need it.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

src/target/arm11_dbgtap.c

@@ -24,6 +24,7 @@
 #include "config.h"
 #endif
 
+#include "arm_jtag.h"
 #include "arm11_dbgtap.h"
 
 #include "time_support.h"