phy: samsung: Replace zero-length array with flexible-array

There is a regular need in the kernel to provide a way to declare having a
dynamically sized set of trailing elements in a structure. Kernel code should
always use “flexible array members”[1] for these cases. The older style of
one-element or zero-length arrays should no longer be used[2].

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://github.com/KSPP/linux/issues/21Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

drivers/phy/samsung/phy-samsung-usb2.h

@@ -43,7 +43,7 @@ struct samsung_usb2_phy_driver {
 	struct regmap *reg_pmu;
 	struct regmap *reg_sys;
 	spinlock_t lock;
-	struct samsung_usb2_phy_instance instances[0];
+	struct samsung_usb2_phy_instance instances[];
 };
 
 struct samsung_usb2_common_phy {