ARM: s3c64xx: switch to generic watchdog driver reset

Similarly to commit f6361c6b3880 ("ARM: S3C24XX: remove separate restart
code"), the platform watchdog reset code can be removed in favor of
a generic watchdog driver which already handles reset.

This allows removal of a bunch of machine code and fixes also W=1
compile warnings:

    arch/arm/plat-samsung/watchdog-reset.c:29:6: warning: no previous prototype for 'samsung_wdt_reset' [-Wmissing-prototypes]
    arch/arm/plat-samsung/watchdog-reset.c:69:13: warning: no previous prototype for 'samsung_wdt_reset_of_init' [-Wmissing-prototypes]
    arch/arm/plat-samsung/watchdog-reset.c:89:13: warning: no previous prototype for 'samsung_wdt_reset_init' [-Wmissing-prototypes]

The generic watchdog-based system reset is not exactly the same as
before.  The previous method had a fallback to soft_restart() which now
is gone.

The commit also removes a FIXME note about calling s3c64xx_clk_init()
inside s3c64xx_init_irq().  No one fixed this since long time and the
note is not meaningful anymore because watchdog part is removed.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Tomasz Figa <tomasz.figa@gmail.com>
diff --git a/arch/arm/mach-s3c64xx/Kconfig b/arch/arm/mach-s3c64xx/Kconfig
index e208c2b..f3fcb57 100644
--- a/arch/arm/mach-s3c64xx/Kconfig
+++ b/arch/arm/mach-s3c64xx/Kconfig
@@ -18,9 +18,10 @@
 	select PM_GENERIC_DOMAINS if PM
 	select S3C_DEV_NAND if ATAGS
 	select S3C_GPIO_TRACK if ATAGS
+	select S3C2410_WATCHDOG
 	select SAMSUNG_ATAGS if ATAGS
 	select SAMSUNG_WAKEMASK if PM
-	select SAMSUNG_WDT_RESET
+	select WATCHDOG
 	help
 	  Samsung S3C64XX series based systems