spd: trusty: add SET_ROT_PARAMS handling

If Trusty is not running on the device, then Verified Boot is
not supported and the NS layer will fail gracefully later during
boot. This patch just returns success for the case when Trusty is
not running on the device and the bootloader issues SET_ROT_PARAMS
call during boot, so that we can at least boot non-Android images.

Change-Id: I40fc249983df80fb8cc5be5e4ce94c99d5b5f17d
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>