staging: wfx: sta and dtim

wfx_ps_notify() is called for any changes in the TIM. However,
association ID 0 is a very special case that should be handled
independently.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200115135338.14374-55-Jerome.Pouiller@silabs.com


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