rtlwifi: rtl8723be: Remove set but unused variable 'cck_highpwr'

rtlwifi: rtl8723be: Remove set but unused variable 'cck_highpwr'

Fixes the following W=1 kernel build warning(s):

 drivers/net/wireless/realtek/rtlwifi/rtl8723be/trx.c: In function ‘_rtl8723be_query_rxphystatus’:
 drivers/net/wireless/realtek/rtlwifi/rtl8723be/trx.c:53:6: warning: variable ‘cck_highpwr’ set but not used [-Wunused-but-set-variable]

Cc: Ping-Ke Shih <pkshih@realtek.com>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201102112410.1049272-33-lee.jones@linaro.org