qtnfmac: simplify error reporting in regulatory notifier

Error reporting in qtnf_cfg80211_reg_notifier only requires to print
one type of message and an error code. Firmware will report success
for an attempt to set regulatory region to the same value,
so no special handling is required for this case.

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