firmware: rsu: add device attributes to sysfs interface

Add the following device attributes to Intel Stratix10 Remote System
Update (RSU) sysfs interface:
	dcmf0
	dcmf1
	dcmf2
	dcmf3
	max_retry

Signed-off-by: Richard Gong <richard.gong@intel.com>
Link: https://lore.kernel.org/r/1592231348-31334-5-git-send-email-richard.gong@linux.intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>