fs: fc_log replace magic number 7 with ARRAY_SIZE()

Replace the hardcoded value `7` in `put_fc_log()` with `ARRAY_SIZE`.
This improves maintainability by ensuring the loop adapts to changes
in the buffer size.

Signed-off-by: Guo Weikang <guoweikang.kernel@gmail.com>
Link: https://lore.kernel.org/r/20241202081146.1031780-1-guoweikang.kernel@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: guoweikang

fs/fs_context.c

@@ -493,7 +493,7 @@ static void put_fc_log(struct fs_context *fc)
 	if (log) {
 		if (refcount_dec_and_test(&log->usage)) {
 			fc->log.log = NULL;
-			for (i = 0; i <= 7; i++)
+			for (i = 0; i < ARRAY_SIZE(log->buffer) ; i++)
 				if (log->need_free & (1 << i))
 					kfree(log->buffer[i]);
 			kfree(log);