usb: Update USB oem function Let default USB oem function be "diag[,adb]" to align with previous projects. Bug: 142104881 Test: diag port is enabled while bootmode=factory Change-Id: I9bd290b8ef0d2ced19fd7f5c63bc0f922a72e9e6 Signed-off-by: pumahsu <pumahsu@google.com>