watchdog: s3c2410_wdt: use exynos_get_pmu_regmap_by_phandle() for PMU regs

watchdog: s3c2410_wdt: use exynos_get_pmu_regmap_by_phandle() for PMU regs

Obtain the PMU regmap using the new API added to exynos-pmu driver rather
than syscon_regmap_lookup_by_phandle(). As this driver no longer depends
on mfd syscon remove that header and Kconfig dependency.

Tested-by: Alexey Klimov <alexey.klimov@linaro.org>
Tested-by: Sam Protsenko <semen.protsenko@linaro.org>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
Link: https://lore.kernel.org/r/20240220220613.797068-3-peter.griffin@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>