dm: reset: Update uclass to allow querying reset status

Add a reset operations function pointer to support querying the current
status of a reset control.

Reviewed-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Andreas Dannenberg <dannenberg@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>