exfat: remove unnecessary reassignment of p_uniname->name_len

kbuild test robot reported :

	fs/exfat/nls.c:531:22: warning: Variable 'p_uniname->name_len'
	is reassigned a value before the old one has been used.

The reassignment of p_uniname->name_len is not needed and remove it.

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Git-commit: f78059805fb9fc5c343e89f39cf11856d047dd60
Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


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