CRIS v10: Cleanup of drivers/gpio.c

CRIS v10: Cleanup of drivers/gpio.c

- Change parameters of gpio_write (const char * buf -> const char __user *buf)
- Don't initialize static variables to zero.
- Remove useless casts from void.
- Change name of interrupt routine (gpio_pa_interrupt -> gpio_interrupt)
- Use kzmalloc instead of allocating memory and zeroing it manually.
- Correct casts for copy_to_user and copy_from_user to (void __user *)
- Make file_operations gpio_fops static.
- Make ioif_watcher static, not used outside this file.