staging: wfx: avoid double warning when no more tx policy are available

Currently, number of available tx retry policies is checked two times.
Only one is sufficient.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20191217161318.31402-14-Jerome.Pouiller@silabs.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>