rtl8188eu: Fix a possible sleep-in-atomic bug in _rtw_pwr_wakeup

The driver may sleep under a spinlock, and the function call path is:
rtw_set_802_11_disassociate(acquire the spinlock)
  _rtw_pwr_wakeup
    usleep_range --> may sleep

To fix it, usleep_range is replaced with udelay.
This bug is found by my static analysis tool and my code review.
Signed-off-by: Jia-Ju Bai <baijiaju1990@163.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8188eu/core/rtw_pwrctrl.c

@@ -570,7 +570,7 @@ int _rtw_pwr_wakeup(struct adapter *padapter, u32 ips_deffer_ms, const char *cal
 		DBG_88E("%s wait ps_processing...\n", __func__);
 		while (pwrpriv->ps_processing &&
 		       jiffies_to_msecs(jiffies - start) <= 3000)
-			usleep_range(1000, 3000);
+			udelay(1500);
 		if (pwrpriv->ps_processing)
 			DBG_88E("%s wait ps_processing timeout\n", __func__);
 		else