Remove duplicated codes

Remove duplicated codes

- Issue:
The codes for checking preconditions are repeated in every functions. And also,
the codes for clearing list are repeated.

- Solution:
This patch makes new inline functions for simplify the precondtion
checking code. Using theses new functions, we can remove many duplicated
precondition checking code.
And also, this patch makes new function for clearing voice information list.
Through this function, we can remove duplicated list clearing code.

Change-Id: I611c798238b76b3e2d0b50942dc3b3c5d0eb2372
Signed-off-by: Suyeon Hwang <stom.hwang@samsung.com>