virt_wifi: Return micros for BSS TSF values

[ Upstream commit b57aa17f

 ]

cfg80211_inform_bss expects to receive a TSF value, but is given the
time since boot in nanoseconds. TSF values are expected to be at
microsecond scale rather than nanosecond scale.

Signed-off-by: A. Cody Schuffelen <schuffelen@google.com>
Link: https://lore.kernel.org/r/20210318200419.1421034-1-schuffelen@google.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>