include: remove superfluous definition from internal.h

Get rid of definitions that we no longer need.

And move trau_frame_idle() definition where it really belongs to.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/include/osmocom/abis/trau_frame.h b/include/osmocom/abis/trau_frame.h
index a76da33..64bec2b 100644
--- a/include/osmocom/abis/trau_frame.h
+++ b/include/osmocom/abis/trau_frame.h
@@ -59,5 +59,6 @@
 int encode_trau_frame(uint8_t *trau_bits, const struct decoded_trau_frame *fr);
 int trau_frame_up2down(struct decoded_trau_frame *fr);
 
+uint8_t *trau_idle_frame(void);
 
 #endif /* _TRAU_FRAME_H */