fs/affs/file.c: fix direct IO writes beyond EOF

Use the same fallback to normal IO in case of write
operations beyond EOF as fat direct IO. This patch fixes

fsx file -d -Z -r 4096 -w 4096

Report:
  129(129 mod 256): TRUNCATE DOWN from 0x3ff01 to 0xb3f6
  130(130 mod 256): WRITE    0x22000 thru 0x2dfff (0xc000 bytes) HOLE

Thanks to Jan for helping me on this problem.

The ideal solution suggested by Jan Kara would be to use
cont_write_begin() but affs direct_IO shouldn't be used a lot anyway...

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>