staging: dgnc: replace udelay with usleep_range

Fix checkpatch warning on dgnc_cls.c: CHECK usleep_range is preferred
over udelay. udelay(t) in function cls_uart_init is within non-atomic
context and can be safely replaced by usleep_range(t, t + delta) where
delta is t (as t is between 10 and 20 microseconds).
Signed-off-by: Aishwarya Pant <aishpant@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/dgnc/dgnc_cls.c

@@ -1096,7 +1096,7 @@ static void cls_uart_init(struct channel_t *ch)
 
 	writeb(UART_FCR_ENABLE_FIFO | UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT,
 	       &ch->ch_cls_uart->isr_fcr);
-	udelay(10);
+	usleep_range(10, 20);
 
 	ch->ch_flags |= (CH_FIFO_ENABLED | CH_TX_FIFO_EMPTY | CH_TX_FIFO_LWM);