bluetooth: Fix bluetooth on/off issue

On new rome 2.1 chipset, BT_EN pin has been HW pull-up.
The gpio for BT_EN pin on APQ8084 is configured as input
when bt is off, so, the pin is high due to the HW pull-up
from the rome 2.1. Therefore, the gpio for BT_EN on APQ8084
has been fixed to be remained as output when bt is off.

Change-Id: I7dc8d7e020eca0270c2ce8d1124679f4fba455ca
Signed-off-by: Sungjun Park <sjpark@codeaurora.org>