staging: wfx: remove set but not used variable 'tx_priv'

staging: wfx: remove set but not used variable 'tx_priv'

drivers/staging/wfx/queue.c: In function wfx_tx_queues_get:
drivers/staging/wfx/queue.c:484:28: warning: variable tx_priv set but not used [-Wunused-but-set-variable]

commit 2e57865e79cf ("staging: wfx: pspoll_mask make no sense")
left behind this unused variable.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200211140334.55248-1-yuehaibing@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>