vfs: uart/cdcacm/usb_serial_jtag fcntl return read/write state

Author: donghengqaz

components/vfs/vfs_cdcacm.c

@@ -271,7 +271,7 @@ static int cdcacm_fcntl(int fd, int cmd, int arg)
     assert(fd == 0);
     int result;
     if (cmd == F_GETFL) {
-        result = 0;
+        result = O_RDWR;
         if (!s_blocking) {
             result |= O_NONBLOCK;
         }

components/vfs/vfs_uart.c

@@ -299,6 +299,7 @@ static int uart_fcntl(int fd, int cmd, int arg)
     assert(fd >=0 && fd < 3);
     int result = 0;
     if (cmd == F_GETFL) {
+        result |= O_RDWR;
         if (s_ctx[fd]->non_blocking) {
             result |= O_NONBLOCK;
         }

components/vfs/vfs_usb_serial_jtag.c

@@ -245,6 +245,7 @@ static int usb_serial_jtag_fcntl(int fd, int cmd, int arg)
 {
     int result = 0;
     if (cmd == F_GETFL) {
+        result |= O_RDWR;
         if (s_ctx.non_blocking) {
             result |= O_NONBLOCK;
         }