cfg80211: regulatory: reset regdomain in case of error

Reset regdomain to world regdomain in case
of errors in set_regdom() function.

This will fix a problem with such scenario:
- iw reg set US
- iw reg set 00
- iw reg set US
The last step always fail and we get deadlock
in kernel regulatory code. Next setting new
regulatory wasn't possible due to:

Pending regulatory request, waiting for it to be processed...

Signed-off-by: Janusz Dziedzic <janusz.dziedzic@tieto.com>
Acked-by: Luis R. Rodriguez <mcgrof@do-not-panic.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>