adfs: work around bogus sparse warning

fs/adfs/dir_f.c:126:4: warning: do-while statement is not a compound statement

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>