exfat: resolve memory leak from exfat_create_upcase_table()

In the Linux kernel, the following vulnerability has been resolved: exfat: resolve memory leak from exfat_create_upcase_table() If exfat_load_upcase_table reaches end and returns -EINVAL, allocated memory doesn't get freed and while exfat_load_default_upcase_table allocates more memory, leading to a memory leak. Here's link to syzkaller crash report illustrating this issue: https://syzkaller.appspot.com/text?tag=CrashReport&x=1406c201980000