uart: tidy the uart_get_info API

We pass both port and state because the original caller had both to hand.
With all the attribute callers this won't be true so do the conversion in
the function itself.

The current callers all do lock/query/unlock. This won't be true for future
set based cases but there are plenty of get ones that will exist so split
the code with a helper for the future cases.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>