Fixes these build errors:

In file included from drivers/tty/serial/sccnxp.c:20:0:
include/linux/serial_core.h: In function 'uart_handle_break':
include/linux/serial_core.h:543:30: error: dereferencing pointer to incomplete type
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Acked-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>