soc: qcom: pmic_glink: add subsystem restart (SSR) support

Add support for PMIC Glink clients to receive notification when
the subsystem goes down and comes up again. PMIC Glink client
can pass a function pointer state_cb via which they would like
to receive when PMIC Glink state transitions so that they can
unregister from the framework (e.g. UCSI) and clean up their
state as needed.

PMIC Glink device supports SSR for the subsystem specified under
"qcom,subsys-name" property.

Change-Id: I0f32f638d72a13e231e6813fb3d782c8fa7a4af0
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>