Staging: comedi: jr3_pci.c: add required includes

Fix this build errors:
jr3_pci.c:739: error: 'jiffies' undeclared
jr3_pci.c:748: error: implicit declaration of function 'msecs_to_jiffies'
jr3_pci.c:763: error: implicit declaration of function 'add_timer'
jr3_pci.c:790: error: implicit declaration of function 'init_timer'
jr3_pci.c:951: error: implicit declaration of function 'del_timer_sync'

Signed-off-by: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>