Add synchroniztaion to prevent concurrent modification exception

Fix unsynchronized concurrent use.

Bug: 141503388
Test: atest com.android.server.wifi.HalDeviceManagerTest
Change-Id: Ibe3ffccfca4d175e3f6eb57b202ae0d76d5f33ef
(cherry picked from commit 175e0b8a9bbaf173d02bde574de5c22f82617f51)
1 file changed