wlcore: update beacon and probe_resp templates when rates change

When the data rates change, we get BSS_CHANGED_BASIC_RATES.  At this
point, we should update all the templates to match the new rates.  We
were changing some of the templates, but the beacon and the probe
response templates were missing.

[Remove redundant min_rate variable - Arik]

Signed-off-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: Arik Nemtsov <arik@wizery.com>