exfat: Simplify exfat_utf8_d_cmp() for code points above U+FFFF

If two Unicode code points represented in UTF-16 are different then also
their UTF-32 representation must be different. Therefore conversion from
UTF-32 to UTF-16 is not needed.

Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Git-commit: 197298a64983e2beaf1a87413daff3044b4f3821
Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: lixiang <lixiang@codeaurora.org>