[SCSI] libfcoe: Add fcoe_sysfs

[SCSI] libfcoe: Add fcoe_sysfs

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_loss_tmo

A device loss infrastructre similar to the FC Transport's
is also added by this patch. It is nice to have so that a
link flapping adapter doesn't continually advance the count
used to identify the discovered FCF. FCFs will exist in a
"Disconnected" state until either the timer expires or the
FCF is rediscovered and becomes "Connected."

This patch generates a few checkpatch.pl WARNINGS that
I'm not sure what to do about. They're macros modeled
around the FC Transport attribute building macros, which
have the same 'feature' where the caller can ommit a cast
in the argument list and no cast occurs in the code. I'm
not sure how to keep the code condensed while keeping the
macros. Any advice would be appreciated.

Signed-off-by: Robert Love <robert.w.love@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>