serial: port: Introduce a common helper to read properties

Several serial drivers want to read the same or similar set of
the port properties. Make a common helper for them.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240304123035.758700-4-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>