fat: Cleanup nls_unload() usage
fat: Cleanup nls_unload() usage

Other users doesn't check NULL explicitly. So, these doesn't also
check to remove inconsistency.

Signed-off-by: OGAWA Hirofumi <1dd685eef08048be95744a1b104ca593a93cc914@mail.parknet.co.jp>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs