cfg80211: rename reg_device_remove() to wiphy_regulatory_deregister()

This makes it clearer what we're doing. This now makes a bit
more sense given that regardless of the wiphy if the cell
base station hint feature is supported we will be modifying the
way the regulatory core behaves.

Signed-off-by: Luis R. Rodriguez <mcgrof@qca.qualcomm.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>