Watchdog: sp5100_tco: Move timer initialization into function

Watchdog: sp5100_tco: Move timer initialization into function

Refactor driver's timer initialization into new function. This is needed
inorder to support adding new device layouts while using common timer
initialization.

Co-developed-by: Robert Richter <rrichter@amd.com>
Signed-off-by: Robert Richter <rrichter@amd.com>
Signed-off-by: Terry Bowman <terry.bowman@amd.com>
Tested-by: Jean Delvare <jdelvare@suse.de>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20220202153525.1693378-2-terry.bowman@amd.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>