brcmfmac: fix invalid permanent MAC address in wiphy

When host driver retrieves mac addresses from dongle, driver copies memory
from drvr->mac to perm_addr. But at the moment, drvr->mac is all zero
array which causes permanent MAC address in wiphy is all zero as well.
To fix this, we set drvr->mac before setting perm_addr.

Signed-off-by: Wright Feng <wright.feng@cypress.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200604071835.3842-3-wright.feng@cypress.com