watchdog: sp5100_tco: Clean up function and variable names

Use more common function and variable names.

Use pdev instead of dev for platform device.
Use sp5100_tco_probe() instead of sp5100_tco_init() for the probe function.
Drop sp5100_tco_cleanup(); just move the code into sp5100_tco_remove().
Use sp5100_tco_init() instead of sp5100_tco_init_module() for the module
initialization function.
Use sp5100_tco_exit() instead of sp5100_tco_cleanup_module() for the module
exit function.
Use consistent defines for accessing the watchdog control register.

Cc: Zoltán Böszörményi <zboszor@pr.hu>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>