Refactor logic for initialzing vc_config_mgr

Refactor logic for initialzing vc_config_mgr

- Issue:
The code in vc_config_mgr_initialize() has high complexity, and other
function has to use indirect method to check whether the module is
initialized.

- Solution:
This patch refactors the vc_config_mgr_initalize() function. Through
this patch, duplicated code in vc_config_mgr_initialize() is removed,
and also the new flag which shows whether the module is initialized is
introduced. The functions in this module will be able to check the
initialization of the module using this new flag.

Change-Id: I6579c3274dbe5ea93fdf6c5bb990f7a98ea0ffae
Signed-off-by: Suyeon Hwang <stom.hwang@samsung.com>