security-manager: fix privilege-to-gid mapping tests

security-manager: fix privilege-to-gid mapping tests

Verification whether privileges are correctly mapped to grouops is based
on an assumption that the privileges used (camera, location) are not mapped
to any groups in the real configuration. But recently the camera privilege has
been mapped to a group "priv_camera" on the image.
To keep the test working, it now uses a different privilege instead ("nfc") that
doesn't have a group associated to it.

Change-Id: I3cb6ae7911abb5c7efab6558ffdb8043714fbce7
Signed-off-by: Rafal Krypa <r.krypa@samsung.com>