Add property to set enrollment device name prefix.

This value is prefixed to device name during trusted device enrollment
BLE advertisement. Its length is limited by BLE advertise data packet.

Bug: 134392301
Test: Verified on device.
Change-Id: Ib2386ab9ace7494af65b81b12f8e38b3b2f28b26

srcs/android/sysprop/CarProperties.sysprop

diff --git a/srcs/android/sysprop/CarProperties.sysprop b/srcs/android/sysprop/CarProperties.sysprop
index a11ecc9..f6c1317 100644
--- a/srcs/android/sysprop/CarProperties.sysprop
+++ b/srcs/android/sysprop/CarProperties.sysprop
@@ -29,4 +29,14 @@
     scope: Internal
     access: ReadWrite
     prop_name: "android.car.systemuser.bootuseroverrideid"
-}
\ No newline at end of file
+}
+
+# String to be prefixed to device name during trusted device enrollment.
+# Max length limit is 4. Chars exceeding length limit will be truncated.
+prop {
+    api_name: "trusted_device_device_name_prefix"
+    type: String
+    scope: Internal
+    access: Readonly
+    prop_name: "ro.android.car.trusteddevice.device_name_prefix"
+}