cfg80211: avoid restoring the regulatory during disconnect

Driver configures the default country code during bootup.
When STA disconnects, cfg80211 restore the regulatory setting
to world domain.cfg80211 should remain in the default country
code and not restore to world reg domain.

Change-Id: I01ccdc4d2831cf252a4b35f9f856f3256d9b7429
CRs-Fixed: 630014
Signed-off-by: Sachin Ahuja <sahuja@codeaurora.org>