platform/chrome: cros_ec_proto: 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-rc1/process/deprecated.html#zero-length-and-one-element-arraysSigned-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

include/linux/platform_data/cros_ec_proto.h

@@ -69,7 +69,7 @@ struct cros_ec_command {
 	uint32_t outsize;
 	uint32_t insize;
 	uint32_t result;
-	uint8_t data[0];
+	uint8_t data[];
 };
 
 /**