Update wifi interface ip state upon receiving ap disable event

When turning on/off SoftAp with high frequency, sometime calling
WifiManager#updateInterfaceIpState with IFACE_IP_MODE_TETHERED
is performed after handling WIFI_AP_STATE_DISABLED event in
WifiServiceImpl while SoftAp is being terminated. This leads to
the issue that SoftAp is unable to start as startSoftAp always
returns "false". This is because mIfaceIpModes in WifiServiceImpl
keeps the mode WifiManager.IFACE_IP_MODE_TETHERED and the CL below
rejects SoftAp start request.

e257c5c9e79e3675375ca20731cfb74df02b1064 @ frameworks/opt/net/wifi
(WifiServiceImpl: Reject startSoftAp when already tethering)

This CL updates the interface ip state upon receiving ap disable
event from Tethering class to set proper state to mIfaceIpModes.

Bug: 134806980
Test: Ran script to turn on/off soft ap frequently
Signed-off-by: Daichi Ueura <daichi.ueura@sony.com>
Change-Id: I2f89214414d93f1aa942fb8a21264a9baae3452a