adb: Open FunctionFS files with more restrictive access modes

This change opens the control, bulk-in, and bulk-out FunctionFS
endpoints with O_RDONLY or O_WRONLY.

Bug: 70349025
Test: Android on Chrome OS can still use ADB
Test: aosp_sailfish-userdebug can still use ADB

Change-Id: I3895b626cf7cec8437c36bdc6c6e6055aaf3777c
1 file changed