ubifs: Fix ubifsload when using ZLIB

ubifs: Fix ubifsload when using ZLIB

Using ZLIB compression with UBIFS fails if last data node is not a size of
UBIFS_BLOCK_SIZE (4096 bytes).

Easiest way to test this is trying to read a file smaller than 4k:
=> ubifsload 41000000 /etc/fstab
Loading file '/etc/fstab' to addr 0x41000000 with size 704 (0x000002c0)...
UBIFS error (pid 0): read_block: bad data node (block 0, inode 2506)
UBIFS error (pid 0): do_readpage: cannot read page 0 of inode 2506, error -22
Error reading file '/etc/fstab'
/etc/fstab not found!
exit not allowed from main input shell.
=>

With this patch:

=> ubifsload 41000000 /etc/fstab
Loading file '/etc/fstab' to addr 0x41000000 with size 704 (0x000002c0)...
Done
=>

Signed-off-by: Veli-Pekka Peltola <veli-pekka.peltola@bluegiga.com>
Cc: kmpark@infradead.org
Tested-by: Andreas Bießmann <andreas.devel@googlemail.com>
Signed-off-by: Stefan Roese <sr@denx.de>