qtnfmac: make regulatory notifier work on per-phy basis

Wireless core calls regulatory notifier for each wiphy and it only
guarantees that bands info is updated for this particular wiphy prior
to calling a notifier. Hence updating all wiphy which belong to driver
in a single notifier callback is redundant and incorrect.

Signed-off-by: Igor Mitsyanko <igor.mitsyanko.os@quantenna.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>