Fix Firmware class name collision

following patch fixes the i2c name collision with i2c-dev.

http://mcentral.de/wiki/index.php/Bugtracker#i2c_core_problem

This issue has been experienced with em28xx and saa7133 based devices.
I discussed that problem with Jean Delvare a while ago and he proposed 
to add a prefix to the class name.

Signed-off-by: Markus Rechberger <markus.rechberger@amd.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>