b43: reload phy and bss settings after core restarts

b43_op_config and b43_op_bss_info_changed apply many settings by directly
writing to hardware registers. These settings are lost as soon as the core
is restarted and the initvals are reloaded. This was discovered because
restarting hostapd led to the beacon interval getting set to ~33s (see
https://dev.openwrt.org/ticket/8033

 for more information).

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>