rtlwifi: Remove set but not used variable 'rtstate'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/net/wireless/realtek/rtlwifi/ps.c: In function rtl_ps_set_rf_state:
drivers/net/wireless/realtek/rtlwifi/ps.c:71:19: warning: variable rtstate set but not used [-Wunused-but-set-variable]

It is not used since commit f1d2b4d338bf ("rtlwifi:
rtl818x: Move drivers into new realtek directory")

Reported-by: Hulk Robot <[e-mail]>
Signed-off-by: zhengbin <[e-mail]>
Signed-off-by: Kalle Valo <[e-mail]>

drivers/net/wireless/realtek/rtlwifi/ps.c

···
 {
 	struct rtl_priv *rtlpriv = rtl_priv(hw);
 	struct rtl_ps_ctl *ppsc = rtl_psc(rtl_priv(hw));
-	enum rf_pwrstate rtstate;
 	bool actionallowed = false;
 	u16 rfwait_cnt = 0;
 
···
 			break;
 		}
 	}
-
-	rtstate = ppsc->rfpwr_state;
 
 	switch (state_toset) {
 	case ERFON: