remsim-client: move from common 'src' directory to 'src/client'

As both the bankd and the server already are in src/bankd and
src/server, respectively: Let's unify this and have the client
also in its own sub-directory.

Change-Id: I67a3a5941434f09f7099c2cdb19c126cea305a73
diff --git a/src/rspro_client_fsm.c b/src/rspro_client_fsm.c
index 758bde7..d5cf04b 100644
--- a/src/rspro_client_fsm.c
+++ b/src/rspro_client_fsm.c
@@ -35,8 +35,8 @@
 #include <osmocom/abis/ipa.h>
 #include <osmocom/gsm/protocol/ipaccess.h>
 
-#include "client.h"
-#include "rspro_util.h"
+#include "debug.h"
+#include "rspro_client_fsm.h"
 
 #define S(x)	(1 << (x))