pseries/lparcfg: Add resource group monitoring

pseries/lparcfg: Add resource group monitoring

Systems can now be partitioned into resource groups. By default all
systems will be part of default resource group. Once a resource group is
created, and resources allocated to the resource group, those resources
will be removed from the default resource group. If a LPAR moved to a
resource group, then it can only use resources in the resource group.

So maximum processors that can be allocated to a LPAR can be equal or
smaller than the resources in the resource group.

lparcfg can now exposes the resource group id to which this LPAR belongs
to. It also exposes the number of processors in the current resource
group. The default resource group id happens to be 0. These would be
documented in the upcoming PAPR update.

Example of an LPAR in a default resource group
root@ltcp11-lp3 $ grep resource_group /proc/powerpc/lparcfg
resource_group_number=0
resource_group_active_processors=50
root@ltcp11-lp3 $

Example of an LPAR in a non-default resource group
root@ltcp11-lp5 $ grep resource_group /proc/powerpc/lparcfg
resource_group_number=1
resource_group_active_processors=30
root@ltcp11-lp5 $

Signed-off-by: Srikar Dronamraju <srikar@linux.ibm.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250716104600.59102-1-srikar@linux.ibm.com