mcb: Fix an error handling path in 'chameleon_parse_cells()'

If 'chameleon_get_bar()' fails, we will return 0, which mean success.
We should return the corresponding error code instead.

Remove the useless initialisation of 'ret' which was hiding the issue.
(if 'ret' is not set, gcc generates a warning ("warning: ‘ret’ may be used
uninitialized in this function"))

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>