lib: remove uncessary #includes from headers

Only include what the header itself needs. The big fish here is
intel-gpu-tools.h. More will follow.

One ugly thing removed here is the duplicated GEN6_TD_CTL #define, one
of which was broken.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

lib/intel_batchbuffer.h

@@ -4,6 +4,7 @@
 #include <stdint.h>
 #include "intel_bufmgr.h"
 #include "igt_core.h"
+#include "intel_reg.h"
 
 #define BATCH_SZ 4096
 #define BATCH_RESERVED 16