rt2800: enable TX_PIN_CFG_LNA_PE_ bits per band

Do not enable TX_PIN_CFG_LNA_PE_A* bits for 2.4GHz band and
vice versa TX_PIN_CFG_LNA_PE_G* bits for 5GHz.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>