Specify all configurations on qti_default.mk, and here are some
important items:
* QCOM_BLUETOOTH_USING_DIAG = false
* TARGET_BLUETOOTH_UART_DEVICE = "/dev/ttySAC18"
* UART_USE_TERMIOS_AFC = true
* TARGET_USE_QTI_BT_OBS = true
Bug: 202113218
Test: Build pass
Change-Id: I444d64e7413d1b08aff295e3ad64238cbaec1286