[PATCH] IPMI: Fix device model name

Add the product id to the driver model platform device name, in addition to
the device id.  The IPMI spec does not require that individual BMCs in a
system have unique devices IDs, but it does require that the product id/device
id combination be unique.

This also removes a redundant check and cleans up error handling
when the sysfs registration fails.

Signed-off-by: Corey Minyard <minyard@acm.org>
Cc: Carol Hebert <cah@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>