Add get_board_id_gpio()

Actually this change renames get_board_id() to get_board_id_gpio() and
adds a new get_board_id() which calls get_board_id_gpio(). A follow-up
changes adds more logic to get_board_id().

Change-Id: I9edbad290337e48eace88d9e444554caa4bfbf8f
2 files changed