8250: Fix capabilities when changing the port type

When changing the port type, the capabilities flags should be changed
also, otherwise the capabilities will not correspond to the port type,
which make set_sleep() crash on rmmod.

This patch just assign the correct capabilites when the port changes.

Signed-off-by: Breno Leitao <leitao@linux.vnet.ibm.com>
CC: Michael Reed <mreed@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>