Staging: comedi: fix memory leak in comedi_bond.c

We allocate bdev and then krealloc the devs pointer in order to add bdev
at the end of the devpriv->devs array list.  But if for some reason this
krealloc fails, we need to free bdev before returning an error otherwise
this memory is leaked.

Signed-off-by: Chase Southwood <chase.southwood@yahoo.com>
Acked-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>