platform/mellanox: mlxbf-bootctl: use sysfs_emit() instead of sprintf()

Follow the advice in Documentation/filesystems/sysfs.rst:
show() should only use sysfs_emit() or sysfs_emit_at() when formatting
the value to be returned to user space.

Signed-off-by: Ai Chao <aichao@kylinos.cn>
Acked-by: Vadim Pasternak <vadimp@nvidia.com>
Link: https://lore.kernel.org/r/20250116080836.2890442-1-aichao@kylinos.cn
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

drivers/platform/mellanox/mlxbf-bootctl.c

@@ -177,7 +177,7 @@ static ssize_t post_reset_wdog_show(struct device *dev,
 	if (ret < 0)
 		return ret;
 
-	return sprintf(buf, "%d\n", ret);
+	return sysfs_emit(buf, "%d\n", ret);
 }
 
 static ssize_t post_reset_wdog_store(struct device *dev,
@@ -206,7 +206,7 @@ static ssize_t mlxbf_bootctl_show(int smc_op, char *buf)
 	if (action < 0)
 		return action;
 
-	return sprintf(buf, "%s\n", mlxbf_bootctl_action_to_string(action));
+	return sysfs_emit(buf, "%s\n", mlxbf_bootctl_action_to_string(action));
 }
 
 static int mlxbf_bootctl_store(int smc_op, const char *buf, size_t count)
@@ -274,14 +274,14 @@ static ssize_t lifecycle_state_show(struct device *dev,
 	 * due to using the test bits.
 	 */
 	if (test_state) {
-		return sprintf(buf, "%s(test)\n",
+		return sysfs_emit(buf, "%s(test)\n",
 			       mlxbf_bootctl_lifecycle_states[lc_state]);
 	} else if (use_dev_key &&
 		   (lc_state == MLXBF_BOOTCTL_SB_LIFECYCLE_GA_SECURE)) {
-		return sprintf(buf, "Secured (development)\n");
+		return sysfs_emit(buf, "Secured (development)\n");
 	}
 
-	return sprintf(buf, "%s\n", mlxbf_bootctl_lifecycle_states[lc_state]);
+	return sysfs_emit(buf, "%s\n", mlxbf_bootctl_lifecycle_states[lc_state]);
 }
 
 static ssize_t secure_boot_fuse_state_show(struct device *dev,
@@ -332,9 +332,9 @@ static ssize_t secure_boot_fuse_state_show(struct device *dev,
 			else
 				status = valid ? "Invalid" : "Free";
 		}
-		buf_len += sprintf(buf + buf_len, "%d:%s ", key, status);
+		buf_len += sysfs_emit(buf + buf_len, "%d:%s ", key, status);
 	}
-	buf_len += sprintf(buf + buf_len, "\n");
+	buf_len += sysfs_emit(buf + buf_len, "\n");
 
 	return buf_len;
 }