nimble/gap: Make ble_gap_slave table
nimble/gap: Make ble_gap_slave table

This is in preparation for multiple advertising instance support.

X-Original-Commit: 6af7f52a8b1707d157469d013bb0d91cabdf3eae

apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble