sta_set_security: Fix spelling of GroupMgntCipher

The CAPI argument name is spelled with "Mgnt".. This fixes the spelling,
but the actual functionality remains to-be-implemented.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
diff --git a/sta.c b/sta.c
index fd45f61..26753df 100644
--- a/sta.c
+++ b/sta.c
@@ -1417,7 +1417,7 @@
 		}
 	}
 
-	val = get_param(cmd, "GroupMgmtCipher");
+	val = get_param(cmd, "GroupMgntCipher");
 	if (val) {
 		/* TODO */
 	}