bus: ti-sysc: Check for lost context in sysc_reinit_module()

bus: ti-sysc: Check for lost context in sysc_reinit_module()

There is no need to restore context if it was not lost. Let's add a new
function sysc_check_context() to check for lost context. To make use of it,
we need to save the sysconfig register status on enable and disable.

Signed-off-by: Tony Lindgren <tony@atomide.com>