Revert "wireless: Use first phyX name available when registering phy devices."

This reverts commit 5a254ffe.

The commit failed to take into account that allocated wireless devices
(wiphys) are not added into the device list upon allocation, but only
when they are registered. Therefore, it opened up a race between
allocating and registering a name, so that if two processes allocate and
register concurrently ("alloc, alloc, register, register" rather than
"alloc, register, alloc, register") the code will attempt to use the
same name twice.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>