tty: serial: allow ports to override the irq handler
tty: serial: allow ports to override the irq handler

Some serial ports may have unusal requirements for interrupt handling
(e.g. the Synopsys DesignWare 8250-alike port and it's busy detect
interrupt).  Add a .handle_irq callback that can be used for platforms
to override the interrupt behaviour in a similar fashion to the
.serial_out and .serial_in callbacks.

Signed-off-by: Jamie Iles <b4dde37aa2aac745c0e6c43447507eaeace3e59f@jamieiles.com>
Acked-by: Alan Cox <91e38e63b890fbb214c8914809fde03c73e7f24d@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <4645f7897fd33786a2ee1264d590b3c400559d85@suse.de>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs