staging: rtl8723bs: remove unused 'poll_cnt' from rtw_set_rpwm()

The 'poll_cnt' is used to assist in polling hardware state. Current code
uses jiffies to determine timeout, so removing this value is safe.

Otherwise, clang warns:

core/rtw_pwrctrl.c:288:6: warning:
	 variable 'poll_cnt' set but not used [-Wunused-but-set-variable]
  288 |                 u8 poll_cnt = 0;
      |                    ^
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Link: https://lore.kernel.org/r/20240913002815.5149-5-pkshih@realtek.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8723bs/core/rtw_pwrctrl.c

@@ -284,14 +284,12 @@ void rtw_set_rpwm(struct adapter *padapter, u8 pslv)
 	if (rpwm & PS_ACK) {
 		unsigned long start_time;
 		u8 cpwm_now;
-		u8 poll_cnt = 0;
 
 		start_time = jiffies;
 
 		/*  polling cpwm */
 		do {
 			mdelay(1);
-			poll_cnt++;
 			rtw_hal_get_hwreg(padapter, HW_VAR_CPWM, &cpwm_now);
 			if ((cpwm_orig ^ cpwm_now) & 0x80) {
 				pwrpriv->cpwm = PS_STATE_S4;