watchdog: s3c2410: Extract disable and mask code into separate functions

The s3c2410wdt_mask_and_disable_reset() function content is bound to be
changed further. Prepare it for upcoming changes by splitting into
separate "mask reset" and "disable reset" functions. But keep
s3c2410wdt_mask_and_disable_reset() function present as a facade.

This commit doesn't bring any functional change to existing devices, but
merely provides an infrastructure for upcoming chips support.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20211107202943.8859-7-semen.protsenko@linaro.org


Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>