Fix compiler warnings (#6023)

components/drivers/hwcrypto/hw_bignum.c

@@ -129,7 +129,7 @@ int rt_hwcrypto_bignum_export_bin(struct hw_bignum_mpi *n, rt_uint8_t *buf, int
         return 0;
     }
     rt_memset(buf, 0, len);
-    cp_len = n->total > len ? len : n->total;
+    cp_len = (int)n->total > len ? len : (int)n->total;
     for(i = cp_len, j = 0; i > 0; i--, j++)
     {
         buf[i - 1] = n->p[j];
@@ -156,7 +156,7 @@ int rt_hwcrypto_bignum_import_bin(struct hw_bignum_mpi *n, rt_uint8_t *buf, int
     {
         return 0;
     }
-    if (n->total < len)
+    if ((int)n->total < len)
     {
         temp_p = rt_malloc(len);
         if (temp_p == RT_NULL)
@@ -170,7 +170,7 @@ int rt_hwcrypto_bignum_import_bin(struct hw_bignum_mpi *n, rt_uint8_t *buf, int
 
     n->sign = 1;
     rt_memset(n->p, 0, n->total);
-    cp_len = n->total > len ? len : n->total;
+    cp_len = (int)n->total > len ? len : n->total;
 
     for(i = cp_len, j = 0; i > 0; i--, j++)
     {

components/libc/posix/io/poll/poll.c

@@ -154,7 +154,7 @@ static int poll_do(struct pollfd *fds, nfds_t nfds, struct rt_poll_table *pt, in
 {
     int num;
     int istimeout = 0;
-    int n;
+    nfds_t n;
     struct pollfd *pf;
     int  ret = 0;
 

components/net/netdev/src/netdev.c

@@ -1066,7 +1066,8 @@ int netdev_cmd_ping(char* target_name, char *netdev_name, rt_uint32_t times, rt_
 
     struct netdev *netdev = RT_NULL;
     struct netdev_ping_resp ping_resp;
-    int index, ret = 0;
+    rt_uint32_t index;
+    int ret = 0;
 
     if (size == 0)
     {

components/net/sal/src/sal_socket.c

@@ -376,7 +376,8 @@ static void sal_unlock(void)
  */
 int sal_netdev_cleanup(struct netdev *netdev)
 {
-    int idx = 0, find_dev;
+    uint32_t idx = 0;
+    int find_dev;
 
     do
     {