liquidio: fix issues with fw_type module parameter

The fw_type module parameter isn't showing up in the
/sys/module/liquidio/parameters directory.  Fix it by setting the read
permission bits for user, group, other in module_param_string().  Revise
the description of fw_type.  Initialize the fw_type static char array with
the default value to conform to the module parameter description.

Signed-off-by: Derek Chickles <derek.chickles@cavium.com>
Signed-off-by: Felix Manlunas <felix.manlunas@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>