Remove unnecessary close_device_and_disk()

1) lp_disk is not used and assigned NULL so doesn't need closing.
2) lp_device is already ped_device_open()ed and ped_device_close()d
within the above while loop.  lp_device will be set to NULL when the
while loop ends so this doesn't need closing either.  Hence
close_device_and_disk() is always passed with two NULL pointers and is a
no operation so can be removed.

src/GParted_Core.cc

@@ -240,8 +240,6 @@ void GParted_Core::set_devices( std::vector<Device> & devices )
 			}
 			lp_device = ped_device_get_next( lp_device ) ;
 		}
-		PedDisk* lp_disk = NULL ;
-		close_device_and_disk( lp_device, lp_disk ) ;
 
 		std::sort( device_paths .begin(), device_paths .end() ) ;
 	}