Fix: left shift cannot be repesented in type int

Caught by ASan:
runtime error: left shift of 1 by 31 places cannot be represented in type 'int'

Change-Id: I30aed795d027dc063f06e08c8455bad2dd92cf24
diff --git a/src/pcu_vty.c b/src/pcu_vty.c
index c2de92c..abc3d8d 100644
--- a/src/pcu_vty.c
+++ b/src/pcu_vty.c
@@ -239,7 +239,7 @@
 		vty_out(vty, " pcu-socket %s%s", the_pcu->pcu_sock_path, VTY_NEWLINE);
 
 	for (i = 0; i < 32; i++) {
-		unsigned int cs = (1 << i);
+		uint32_t cs = ((uint32_t)1 << i);
 		if (the_pcu->gsmtap_categ_mask & cs) {
 			vty_out(vty, " gsmtap-category %s%s",
 				get_value_string(pcu_gsmtap_categ_names, i), VTY_NEWLINE);