soc: hab: add size checking when hab import buffer

soc: hab: add size checking when hab import buffer

If the input size of import buffer isn't equal to
the real size of this buffer, hab should reject this
import function.

Change-Id: I184a0752d37e9f1bf6a8705ccf8f2fdfd6796d5e
Signed-off-by: Yajun Li <yajunl@codeaurora.org>