libpayload: Use __func__ instead of old __FUNCTION__

Change-Id: Ic3c22ac101a2ff44f97b2ac3fe3c0a89391718de
Signed-off-by: Elyes Haouas <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/72380
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Singer <felixsinger@posteo.net>

payloads/libpayload/include/die.h

@@ -35,7 +35,7 @@ void die_work(const char *file, const char *func, const int line,
 	__attribute__((noreturn));
 
 #define die(fmt, args...) \
-	do { die_work(__FILE__, __FUNCTION__, __LINE__, fmt, ##args); } \
+	do { die_work(__FILE__, __func__, __LINE__, fmt, ##args); } \
 	while (0)
 
 #define die_if(condition, fmt, args...) \