mhi: core: fix incorrect mhi device probe failure

mhi device drivers do not always required to assign a status_cb
function pointer during driver registration. Fail probe only
if selected device requires notifications from MHI host and
status_cb is not assigned.

CRs-Fixed: 2237541
Change-Id: Ie26737f0f281e172007f7b468d7b072d589341df
Signed-off-by: Sujeev Dias <sdias@codeaurora.org>