watchdog: Fix SPL build with watchdog disabled in asm files

Allow to compile assembler files in SPL build which calls WATCHDOG_RESET
function when watchdog is disabled in SPL and enabled in U-Boot proper.

This issue was fixed in past by commit 7fbd42f5afc4 ("watchdog: Handle SPL
build with watchdog disabled") for C source files, but not for assembler
source files.

Currently the only assembler source file which calls WATCHDOG_RESET is
arch/powerpc/lib/ticks.S, so this patch affects and fixes powerpc SPL
builds.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/include/watchdog.h b/include/watchdog.h
index 14fa5fd..813cc8f 100644
--- a/include/watchdog.h
+++ b/include/watchdog.h
@@ -49,7 +49,13 @@
 	 */
 	#if defined(CONFIG_WATCHDOG)
 		#if defined(__ASSEMBLY__)
-			#define WATCHDOG_RESET bl watchdog_reset
+			/* Don't require the watchdog to be enabled in SPL */
+			#if defined(CONFIG_SPL_BUILD) &&		\
+				!defined(CONFIG_SPL_WATCHDOG)
+				#define WATCHDOG_RESET /*XXX DO_NOT_DEL_THIS_COMMENT*/
+			#else
+				#define WATCHDOG_RESET bl watchdog_reset
+			#endif
 		#else
 			/* Don't require the watchdog to be enabled in SPL */
 			#if defined(CONFIG_SPL_BUILD) &&		\