Do not clear Wifi country code upon entering airplane mode

Previously, Wifi and telephony would both clear the country code
upon entering airplane mode, and telephony would update the Wifi
country code upon exiting airplane mode.

Now telephony no longer clears the country code immediately upon
entering airplane mode, but Wifi will still clear its country
code immediately. If airplane mode is exited before telephony
clears the country code, telephony will not update Wifi's
country code since it believes that Wifi still has it's previous
country code.

With a cleared country code, Wifi hotspot will always use the
2.4 GHz band, even when the user specified that 5 GHz
is preferred.

Fix this by not clearing the Wifi country code immediately upon
entering airplane mode. Telephony will do the right thing and
clear/update the Wifi country code as needed.

Bug: 140392836
Test: atest FrameworksWifiTests
Test: reboot device, turn airplane mode on, then quickly
turn it off, turn on hotspot with 5 GHz preferred, verify
that hotspot is indeed on 5 GHz band.

Change-Id: I80ab05bed795453077fc1d9d476d91fda1db5ddf
Merged-In: I80ab05bed795453077fc1d9d476d91fda1db5ddf
3 files changed