exfat: Remove unused functions exfat_high_surrogate() and exfat_low_surrogate()

After applying previous two patches, these functions are not used anymore.

Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Git-commit: 6778337a7a4e51ec9fa4a76846d34e8a66ca6418
Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


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