rlc: replace int with uint16_t

The i value will only count forward and is limited to 11 bit. The integer is also
converted when returning to uint16_t

Change-Id: Ib8a9081bbcb8b4344498254c58941002d17f9381
diff --git a/src/rlc.cpp b/src/rlc.cpp
index e5067c9..c6d4330 100644
--- a/src/rlc.cpp
+++ b/src/rlc.cpp
@@ -91,7 +91,7 @@
 /* Update the receive block bitmap */
 uint16_t gprs_rlc_ul_window::update_egprs_rbb(uint8_t *rbb)
 {
-	int i;
+	uint16_t i;
 	uint16_t bsn;
 	uint16_t bitmask = 0x80;
 	int8_t pos = 0;