sparc: replace zero-length array with flexible-array member

The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1],
introduced in C99:

struct foo {
	int stuff;
	struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last, which is beneficial
to cultivate a high-quality code.[2]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Zhang Kunbo <zhangkunbo@huawei.com>
Reviewed-by: Andreas Larsson <andreas@gaisler.com>
Link: https://lore.kernel.org/r/20241218074439.3271397-1-zhangkunbo@huawei.com
Signed-off-by: Andreas Larsson <andreas@gaisler.com>

arch/sparc/kernel/pci.c

@@ -932,7 +932,7 @@ static void pci_bus_slot_names(struct device_node *node, struct pci_bus *bus)
 {
 	const struct pci_slot_names {
 		u32	slot_mask;
-		char	names[0];
+		char	names[];
 	} *prop;
 	const char *sp;
 	int len, i;