qtnfmac: decode error codes from firmware replies

Introduce a function that will map an error code reported in reply
to a firmware command, into one of standard errno codes.
Use additional error codes to improve error reporting
for MAC address changes.

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