sparc64: fix OF path names for sun4v systems

sparc64: fix OF path names for sun4v systems

Fix the Open Firmware (OF) path property for sun4v SPARC systems.
These platforms do not have a /sas/ within their path. Over time
different OF addressing schemes have been supported. There
is no generic addressing scheme that works across every HBA.

It looks that this functionality will not work if you try to cross-install
SPARC GRUB2 binary using e.g. x86 grub-install. By default it should work.
However, we will also have other issues here, like lack of access to OF
firmware/paths, which make such configs unusable anyway. So, let's leave
this patch as is for time being. If somebody cares then he/she should fix
the issue(s) at some point.

Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>