Don't check permissions on API calls in off-line mode

Don't check permissions on API calls in off-line mode

Off-line mode was introduced to be used during image creation, when no
services are running. It enables root to perform some security-manager
operations on the client side.

But in off-line mode not only security-manager isn't running. No services
run, including cynara service. When libsecurity-manager-client tries to
check whether the off-line mode user has access to proper privilege, it
fails because cynara_check() has no off-line mode.

Permission checking in such scenario isn't required. The user is already
checked for UID 0 and even if it gets away from that check, it wouldn't be
able to perform actual operations without being super user.

Change-Id: I087bbc6b29a702a445d4498b96a950ca1e919efd
Signed-off-by: Rafal Krypa <r.krypa@samsung.com>