staging: wfx: prefer to wait for an event instead to sleep

When possible it is better to wait for an explicit event instead of wait
an arbitrary amount of time.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20220225112405.355599-9-Jerome.Pouiller@silabs.com


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