interface_block: rename the sysfs files to not have 'module' in them

The sysfs files for an interface block should not have 'module' in them.
This was a hold-over from when we thought we were going to have
all attributes of a "module" in one directory.  Remove the prefix as
it's not needed, and is confusing considering modules can not have
strings or any of these attributes.

Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
sysfs documentation: Document the greybus interface block sysfs files.

Documentation, what, really?

Yes.

Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
interface_block: move sysfs files into the interface_block.c file

No need to keep these out in sysfs.c, move them into the
interface_block.c file so that we can see them easier, and remove some
variable definitions by taking advantage of the attribute group macro.

Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
connection: document the sysfs files

Document what the sysfs files are for connections, so that people have a
chance to understand what they can be used for.

Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
interface: document sysfs files

Yes, an interface has a device id sysfs file, so we need to document it.

Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>