fs/fat: fix all other checkpatch issues in dir.c

1: Import linux/uaccess.h instead of asm.uaccess.h
2: Stop any lines going over 80 characters
3: Stopped setting any variables in if statements
4: Stopped splitting quoted strings
5: Removed unneeded parentheses

Signed-off-by: Cruz Julian Bishop <cruzjbishop@gmail.com>
Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>