chassishandler: Refactor get/set boot parameters code
chassishandler: Refactor get/set boot parameters code

-Make use of 'getDbusProperty'/'setDbusProperty' library functions
-Remove duplicate log messages on errors

Signed-off-by: Konstantin Aladyshev <966fa2632e4e2a876c19833f9995ee957bdb2a69@gmail.com>
Change-Id: Iadd3b145b2170667ca0d885a6413d1ef86b6fe27

openbmc/phosphor-host-ipmid,openbmc/phosphor-host-ipmid,openbmc/phosphor-host-ipmid