halapi: Add new helper functions to get multiple library names

halapi: Add new helper functions to get multiple library names

In order to get the multiple library namse on device,
add new helper function as following. Firstly, get the number of HAL
backend libraries hal_common_get_backend_count() and the get the library
names by hal_common_get_backend_library_names().

- Get the number of the backend libraries according to the type of HAL module
int hal_common_get_backend_count(enum hal_module module);

- Get the backend library names according to the type of HAL module
int hal_common_get_backend_library_names(enum hal_module module,
                                       char **library_names,
                                       int library_count,
                                       int library_name_size);

Change-Id: If6ecc2f550693768e6e63a572dd99c791984e596
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>