mogami: Configure nShutdown gpio with the driver.

The driver code already knows how to handle BT on/off GPIO properly.

Change-Id: If94243ccaf297aed6b0edda4cc43e26fae109bf6
Revert "mogami: temporary disable bluetooth"

This reverts commit eb85223c230ac560a14a4aa14454c11a4b5442e6.