blaze_defconfig: build Bluetooth as modules

Build the Bluetooth sub-system and the drivers as modules. This is to enable
building the Bluetooth sub-system and drivers via the compat-wireless approach
for enabling BlueTI.

Change-Id: I9465b5fc8ff651c167e48920726592a5080926e6
Signed-off-by: Pavan Savoy <pavan_savoy@ti.com>