TS alloc: print suggested TRX on allocation errors

If TS allocation fails due to unavailable TFI, print TRX which was
suggested to allocator. This simplifies allocator debugging but requires
cosmetic modifications to test output.

Change-Id: Icaf97d71d71985d52dc0bda448c26b19fe5645e7
Related: OS#2282
diff --git a/src/bts.cpp b/src/bts.cpp
index 1669739..72e1621 100644
--- a/src/bts.cpp
+++ b/src/bts.cpp
@@ -495,7 +495,7 @@
 	}
 
 	if (!free_tfis) {
-		LOGP(DRLCMAC, LOGL_NOTICE, "No TFI available.\n");
+		LOGP(DRLCMAC, LOGL_NOTICE, "No TFI available (suggested TRX: %d).\n", use_trx);
 		return -EBUSY;
 	}