watchdog: Handle SPL build with watchdog disabled

This patch adds some checks, so that the watchdog can be enabled in main
U-Boot proper but can be disabled in SPL.

This will be used by some AT91SAM based boards, which might enable the
watchdog in the main U-Boot proper and not in SPL. It will be enabled in
SPL by default there, so no need to configure it there. This approach
saves some space in SPL.
Signed-off-by: NStefan Roese <sr@denx.de>
Cc: Heiko Schocher <hs@denx.de>
Cc: Andreas Bießmann <andreas@biessmann.org>
Cc: Eugen Hristev <eugen.hristev@microchip.com>
Reviewed-by: NHeiko Schocher <hs@denx.de>
Tested on the taurus board:
Tested-by: NHeiko Schocher <hs@denx.de>

include/watchdog.h

@@ -51,9 +51,15 @@ int init_func_watchdog_reset(void);
 		#if defined(__ASSEMBLY__)
 			#define WATCHDOG_RESET bl watchdog_reset
 		#else
-			extern void watchdog_reset(void);
+			/* Don't require the watchdog to be enabled in SPL */
+			#if defined(CONFIG_SPL_BUILD) &&		\
+				!defined(CONFIG_SPL_WATCHDOG_SUPPORT)
+				#define WATCHDOG_RESET() {}
+			#else
+				extern void watchdog_reset(void);
 
-			#define WATCHDOG_RESET watchdog_reset
+				#define WATCHDOG_RESET watchdog_reset
+			#endif
 		#endif
 	#else
 		/*