soc: mediatek: svs: Fix memory leak in svs_enable_debug_write()

In svs_enable_debug_write(), the buf allocated by memdup_user_nul()
is leaked if kstrtoint() fails.

Fix this by using __free(kfree) to automatically free buf, eliminating
the need for explicit kfree() calls and preventing leaks.

Fixes: 13f1bbc ("soc: mediatek: SVS: add debug commands")
Co-developed-by: Jianhao Xu <jianhao.xu@seu.edu.cn>
Signed-off-by: Jianhao Xu <jianhao.xu@seu.edu.cn>
Signed-off-by: Zilin Guan <zilin@seu.edu.cn>
[Angelo: Added missing cleanup.h inclusion]
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

Author: GoodLuck612

drivers/soc/mediatek/mtk-svs.c

@@ -9,6 +9,7 @@
 #include <linux/bits.h>
 #include <linux/clk.h>
 #include <linux/completion.h>
+#include <linux/cleanup.h>
 #include <linux/cpu.h>
 #include <linux/cpuidle.h>
 #include <linux/debugfs.h>
@@ -789,7 +790,7 @@ static ssize_t svs_enable_debug_write(struct file *filp,
 	struct svs_bank *svsb = file_inode(filp)->i_private;
 	struct svs_platform *svsp = dev_get_drvdata(svsb->dev);
 	int enabled, ret;
-	char *buf = NULL;
+	char *buf __free(kfree) = NULL;
 
 	if (count >= PAGE_SIZE)
 		return -EINVAL;
@@ -807,8 +808,6 @@ static ssize_t svs_enable_debug_write(struct file *filp,
 		svsb->mode_support = SVSB_MODE_ALL_DISABLE;
 	}
 
-	kfree(buf);
-
 	return count;
 }