osu: Add module name as prefix to exported functions

osu: Add module name as prefix to exported functions

Add module name as prefix to exported functions.
For example, do_get_board_param() is changed to board_params_getter_do_get_board_param()
by adding prefix of module name (board-params-getter.c).
In addition, add 'static' to function which is not exported to other files.

Change-Id: I8f38d530d13ec7ca8ca6a5b1bd76108b390c2468
Signed-off-by: Unsung Lee <unsung.lee@samsung.com>