net/mlx5: Replace zero-length array with flexible-array member

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://www.kernel.org/doc/html/v5.9/process/deprecated.html#zero-length-and-one-element-arraysSigned-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

include/linux/mlx5/mlx5_ifc.h

@@ -5823,7 +5823,7 @@ struct mlx5_ifc_alloc_modify_header_context_in_bits {
 	u8         reserved_at_68[0x10];
 	u8         num_of_actions[0x8];
 
-	union mlx5_ifc_set_add_copy_action_in_auto_bits actions[0];
+	union mlx5_ifc_set_add_copy_action_in_auto_bits actions[];
 };
 
 struct mlx5_ifc_dealloc_modify_header_context_out_bits {
@@ -9761,7 +9761,7 @@ struct mlx5_ifc_mcda_reg_bits {
 
 	u8         reserved_at_60[0x20];
 
-	u8         data[0][0x20];
+	u8         data[][0x20];
 };
 
 enum {