devlink: Allow large formatted message of binary output

Devlink supports pair output of name and value. When the value is
binary, it must be presented in an array. If the length of the binary
value exceeds fmsg limitation, break the value into chunks internally.

Signed-off-by: Aya Levin <ayal@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>