greybus: manifest: fix bundle descriptor parse

The descriptor list is walked in two points, in the bundle parsing and
cport parsing, this can make the next descriptor pointer in bundle to be
already removed by the cport remove descriptor and become invalid.

So, just get the next bundle until there no more left.

Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>