rt2800: warn if doing VCO recalibration for unknow RF chip

Since we reset TX_PIN_CFG register, we have to finish recalibration.
Warn if this is not possible.

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