fst-manager: use strlcpy instead of strncpy0

strncpy0 mimics the implementation of strlcpy.

Use strlcpy directly instead of re-implementing it.

CRs-Fixed: 1115821
Change-Id: I8cdcc427284ad4f7eb79d12092e1431ec150c014
Signed-off-by: Hamad Kadmany <hkadmany@codeaurora.org>