Bluetooth 5 PHY simplification

Having PHY_LE_* constants defined in four different places, with one
value being different than others is misleading. Leave just PHY_LE_*
definitions in BluetoothDevice, and add PHY_LE*_MASK for the mask used
in PHY update API.

This patch also removes need to translate PHY value between PHY update
request and event, as mask is used for request, and the value is
returned in event.

Bug: 30622771
Test: manual
Change-Id: I897effa1204a024465d55501c83c542566c4d37c
(cherry picked from commit 9e377194)