csn1: Fix an infinite loop in CSN.1 dissector when having more than 255 padding bits

Port of wireshark.git 8b5aa913711b32b1e1bc707919d2a98c1875d443.

Ported-by: Pau Espin Pedrol <pespin@sysmocom.de>
Change-Id: I7f6aecc2c0f300c1a77cd683652969d3f1aa5794
diff --git a/src/csn1.cpp b/src/csn1.cpp
index 493d471..21bb976 100644
--- a/src/csn1.cpp
+++ b/src/csn1.cpp
@@ -1150,7 +1150,7 @@
         {
           while (remaining_bits_len > 0)
           {
-            guint8 bits_to_handle = remaining_bits_len%8;
+            guint bits_to_handle = remaining_bits_len%8;
             if (bits_to_handle > 0)
             {
 	      LOGPC(DCSN1, LOGL_NOTICE, "%" PRIu64 "|", bitvec_read_field(vector, &readIndex, bits_to_handle));