rts5208: Fix a sleep-in-atomic bug in sd_send_cmd_get_rsp

The driver may sleep under a spin lock, and the function call path is:
rtsx_exclusive_enter_ss (acquire the lock by spin_lock)
rtsx_enter_ss

    rtsx_power_off_card
      sd_cleanup_work
        sd_stop_seq_mode
          sd_switch_clock
            sd_ddr_tuning
              sd_ddr_pre_tuning_tx
                sd_send_cmd_get_rsp
                  wait_timeout
                    schedule_timeout -->  may sleep

To fix it, "wait_timeout" is replaced with mdelay in sd_send_cmd_get_rsp.

---
 drivers/staging/rts5208/sd.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index bdd35b6..fed17ff 100644
@@ -226,7 +226,7 @@ static int sd_send_cmd_get_rsp(struct rtsx_chip *chip, u8 cmd_idx,
 				return STATUS_FAIL;
 			}
 			if (rty_cnt<  SD_MAX_RETRY_COUNT) {
-				wait_timeout(20);
+				mdelay(20);
 				rty_cnt++;
 				goto RTY_SEND_CMD;
 			} else {

-- 1.7.9.5