Bluetooth: Added new prototype of HFP feature bitmask.

This function will allow to let the BT stack use
the features supported by the Bluetooth HFP app.

CRs-Fixed: 482189
Change-Id: I9d015562e310ed2901ada91e692083dde7ac4614
(cherry picked from commit cad7f788e01e07659a605a1f61095a503f68563e)
(cherry picked from commit e0e16d9f105400b3339aa48ea99131fce1570029)
(cherry picked from commit 2d6f0d249c89a5cd9ece75a74bfd96c5c3a32068)