Since SERIAL_CORE needs GENERIC_HARDIRQS (see below) and most serial drivers
select it, just add a GENERIC_HARDIRQS dependency to all serial drivers.
Fixes the compile error below:
drivers/tty/serial/serial_core.c: In function ‘uart_set_info’:
drivers/tty/serial/serial_core.c:725:2: error: implicit declaration of function ‘irq_canonicalize’