[msm8x60] Add support for uart in 8660 bootloader.

Initialize and configure UART_DM in legacy mode (without
Data Mover) to support UARt in bootloader.

Features currently supported/unsupported:
- Legacy mode - no Data Mover
- Support RX/TX path
- No TX/RX Flow control
- Polling mechanism rather than Interrupt based
- Watchdog timeout not handled during long wait

Host Configuration:
Speed: 115200
Data bits: 8
Stop bits: 1
Parity: None
Flow control: None

CRs-fixed: 243843

Change-Id: I0296f77a40bf3e2f0e4040774a9820e836ca588e
7 files changed