busybox

nanddump: make dumping read-only partitions work

Make dumping read-only partitions work by opening the device
O_RDONLY; otherwise the open() will fail with -EPERM.

Signed-off-by: Matt Reimer <mreimer@sdgsystems.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>