f2fs: use strncasecmp() simplify the string comparison

{

	size_t slen = strlen(s);

	size_t sublen = strlen(sub);

	int ret;

	if (sublen > slen)

		return 0;

	ret = memcmp(s + slen - sublen, sub, sublen);

	if (ret) {	/* compare upper case */

		int i;

		char upper_sub[8];

		for (i = 0; i < sublen && i < sizeof(upper_sub); i++)

			upper_sub[i] = toupper(sub[i]);

		return !memcmp(s + slen - sublen, upper_sub, sublen);

	}

	return !ret;

	return !strncasecmp(s + slen - sublen, sub, sublen);

}

/*