rename bscconfig.h to config.h, cleanup

Get rid of the legacy name bscconfig.h from osmo-nitb times.

Remove the #include from some of the files that aren't actually using it.

Instead of '#include "../../config.h"', use plain '#include "config.h"'
because we're anyway passing $top_srcdir as -I during compilation.

Change-Id: Id4f683be1f36f0630c83da54e02868aae847aeec
diff --git a/src/libmsc/msc_vty.c b/src/libmsc/msc_vty.c
index bb36392..a3237cd 100644
--- a/src/libmsc/msc_vty.c
+++ b/src/libmsc/msc_vty.c
@@ -23,7 +23,7 @@
 /* NOTE: I would have liked to call this the MSC_NODE instead of the MSC_NODE,
  * but MSC_NODE already exists to configure a remote MSC for osmo-bsc. */
 
-#include "../../bscconfig.h"
+#include "config.h"
 
 #include <inttypes.h>
 #include <limits.h>