staging: wfx: drop useless update of field basic_rate_set

staging: wfx: drop useless update of field basic_rate_set

Basic Rates are already set by hif_join(). hif_join() is also able to
manage possible changes after association.

Firmware also allows to change the Basic Rates with
hif_set_association_mode() but it does not bring anything in our case.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200420160311.57323-10-Jerome.Pouiller@silabs.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>