rt2800: move txstatus pending routine

Move rt2800usb_txstatus_pending routine to rt2800lib. It will be reused
by rt2800mmio code.

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