This patch adds a 'fcoe bus' infrastructure to the kernel
that is driven by changes to libfcoe which allow LLDs to
present FIP (FCoE Initialization Protocol) discovered
entities and their attributes to user space via sysfs.

This patch adds the following APIs-

fcoe_ctlr_device_add
fcoe_ctlr_device_delete
fcoe_fcf_device_add
fcoe_fcf_device_delete

They allow the LLD to expose the FCoE ENode Controller
and any discovered FCFs (Fibre Channel Forwarders, e.g.
FCoE switches) to the user. Each of these new devices
has their own bus_type so that they are grouped together
for easy lookup from a user space application. Each
new class has an attribute_group to expose attributes
for any created instances. The attributes are-

fcoe_ctlr_device
* fcf_dev_loss_tmo
* lesb_link_fail
* lesb_vlink_fail
* lesb_miss_fka
* lesb_symb_err
* lesb_err_block
* lesb_fcs_error

fcoe_fcf_device
* fabric_name
* switch_name
* priority
* selected
* fc_map
* vfid
* mac
* fka_peroid
* fabric_state
* dev_lo...