rtl8xxxu: Fix rtl8723bu driver reload issue

The generic disable_rf() function clears bits 22 and 23 in
REG_RX_WAIT_CCA, however we did not re-enable them again in
rtl8723b_enable_rf()

This resolves the problem for me with 8723bu devices not working again
after reloading the driver.
Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Cc: stable@vger.kernel.org # 4.7+
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_8723b.c

@@ -1498,6 +1498,10 @@ static void rtl8723b_enable_rf(struct rtl8xxxu_priv *priv)
 	u32 val32;
 	u8 val8;
 
+	val32 = rtl8xxxu_read32(priv, REG_RX_WAIT_CCA);
+	val32 |= (BIT(22) | BIT(23));
+	rtl8xxxu_write32(priv, REG_RX_WAIT_CCA, val32);
+
 	/*
 	 * No indication anywhere as to what 0x0790 does. The 2 antenna
 	 * vendor code preserves bits 6-7 here.