LoongArch: Replace sprintf() with sysfs_emit()

As Documentation/filesystems/sysfs.rst suggested, show() should only use
sysfs_emit() or sysfs_emit_at() when formatting the value to be returned
to user space.

No functional change intended.

Cc: stable@vger.kernel.org
Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

arch/loongarch/kernel/env.c

@@ -86,7 +86,7 @@ late_initcall(fdt_cpu_clk_init);
 static ssize_t boardinfo_show(struct kobject *kobj,
 			      struct kobj_attribute *attr, char *buf)
 {
-	return sprintf(buf,
+	return sysfs_emit(buf,
 		"BIOS Information\n"
 		"Vendor\t\t\t: %s\n"
 		"Version\t\t\t: %s\n"